# Lighting an Aquarium with PAR instead of Watts



## Vermino

sticky this! and give this man a noble prize!


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## O2surplus

I agree, BUT it's the NOBEL PRIZE, hehe. ( the prize was named after Alfred Nobel: The dude that invented TNT )


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## clang

Hi Hoppy. I'm new here. Have you measured the PAR using 30" tanks like the 20Long, 29g and 37g? Most bulbs, PC, T5HO, T8 and T12, are approximately 22" long. This configuration has approximately 4" of space on each side that is not directly under the bulb. (I know that Coralife has some 30" T5NO and T5HO fixtures with 28" bulbs available and Zoo-Med has some 30" T5HO fixtures with 28" bulbs as well. We can use your presently available charts to find the PAR for these fixtures.) I am interested in the 22" bulbs over 30" tanks because so many people have this size of aquarium. You could probably extrapolate this reading of PAR.

One more question concerns your PAR measurements in the graph showing the distance from front to back. Why are there 10 micromoles difference at 4" from center in the aquarium with no water and the tank with water has 5 micromoles difference. Why is there a difference when measured from front to back? The back side of the aquarium has more PAR than the front side, if I am reading the chart correctly. Why is this? (I am not concerned with the 5 micromoles difference from an aquarium with water in it and one without water.) Why does the PAR increase on the back side verses the front side? It would seem to me that the front side and back side would have similar readings as the distance from center increases.

One last question. Why do the aquariums with water in them have a higher PAR than aquariums without water? I would guess that it would be the other way around. Aquariums without water would have a higher PAR reading that aquariums with 5" of water in them would be my guess.

Thanks,
clang


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## Hoppy

When light shines into an aquarium the air-water interface slightly focuses the light. Beams off center are refracted towards the center. This is why the PAR around the center of the tank goes up when you add water. Near the glass at the front, back, and ends, there is considerable reflection of light back into the tank from the glass-air interface, which increases the PAR near the glass. But, if the glass is less than perfectly clean on either side of the glass the amount reflected back into the water is decreased. As I recall I did those PAR measurements in a 10 gallon tank, which I didn't take pains to clean thoroughly. The glass must have been non-uniformly dirty. This was a few years ago, so my memory of that isn't perfect.

I don't have either a 30 inch long tank, nor a 24 inch long light to do PAR tests with. Most of the data I have comes from others who either post it or PM it to me. Someone with the right tank and light, and access to a PAR meter, needs to do that testing. One thing I do know is that if you raise the light far enough above the top of the tank a short light can light up a tank well enough for our purposes. In fact one good way to light a tank is to use a short, but very bright light (4 bulb T5HO, for example) suspended a foot or more above the tank. That greatly reduces the difference in PAR between the water surface and substrate level, and gives relatively uniform light over the substrate.


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## clang

Hoppy said:


> When light shines into an aquarium the air-water interface slightly focuses the light. Beams off center are refracted towards the center. This is why the PAR around the center of the tank goes up when you add water. Near the glass at the front, back, and ends, there is considerable reflection of light back into the tank from the glass-air interface, which increases the PAR near the glass. But, if the glass is less than perfectly clean on either side of the glass the amount reflected back into the water is decreased. As I recall I did those PAR measurements in a 10 gallon tank, which I didn't take pains to clean thoroughly. The glass must have been non-uniformly dirty. This was a few years ago, so my memory of that isn't perfect.


Thank you very much for the explanation. I understand what you are saying. The air-water interface focuses light somewhat like a magnifying glass does (maybe an odd shaped one) and light reflects off of the sides, front and back somewhat like a mirror. The disparity between the front to back measurements are understandable.



Hoppy said:


> I don't have either a 30 inch long tank, nor a 24 inch long light to do PAR tests with. Most of the data I have comes from others who either post it or PM it to me. Someone with the right tank and light, and access to a PAR meter, needs to do that testing. One thing I do know is that if you raise the light far enough above the top of the tank a short light can light up a tank well enough for our purposes. In fact one good way to light a tank is to use a short, but very bright light (4 bulb T5HO, for example) suspended a foot or more above the tank. That greatly reduces the difference in PAR between the water surface and substrate level, and gives relatively uniform light over the substrate.


I don't have a 30" tank running either, but I read a lot of posts from people that have them. 30" is somewhat of an odd length when looking at lighting options. It seems that lighting is basically designed in one foot or 12" increments, like 24", 36", 48", 60" and 72". This makes 20" and 30" length tanks having fewer lighting choices. 60" fixtures and bulbs for them may be somewhat of an oddball length too.


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## ThatGuyWithTheFish

Does anybody here have a PAR meter I can borrow? I'd like to measure PAR,I'm not sure what to do with my lights. The plaster in the ceiling crumbles too much to hang.


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## livingword26

Definitly sticky. Thanks for the time you put in on this Hoppy. It is a great help.


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## Steve001

Now that we got that cleared up, let's move onto PUR (Photosynthetically Active Radiation)


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## Hoppy

PUR = photosynthetically usable radiation, a concept I haven't yet seen a good reason to dig into. Plants use light from the whole spectrum between about 400 and 700 nanometers wave length. Unlike what many people believe, they also use green light, just not as efficiently as they use blue and red light.

If it was hard to get enough light to grow our plants, we would want to get every advantage we could, and look for bulbs that wouldn't waste any light in the green wave lengths, which, if you think about it, would leave us with very drab looking plants. But, the bigger problem we now have is avoiding too much light, not getting enough light. So, why bother with PUR?


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## Azarakiah

is there anything this guy doesnt know about lighting?


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## Hoppy

Azarakiah said:


> is there anything this guy doesnt know about lighting?


 Yes, a lot more than I do know.:icon_mrgr


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## plantbrain

Hoppy said:


> PUR = photosynthetically usable radiation, a concept I haven't yet seen a good reason to dig into. Plants use light from the whole spectrum between about 400 and 700 nanometers wave length. Unlike what many people believe, they also use green light, just not as efficiently as they use blue and red light.
> 
> If it was hard to get enough light to grow our plants, we would want to get every advantage we could, and look for bulbs that wouldn't waste any light in the green wave lengths, which, if you think about it, would leave us with very drab looking plants. But, the bigger problem we now have is avoiding too much light, not getting enough light. So, why bother with PUR?


The main argument that Daniel suggested in a debate I've had over the years was that with higher PUR, we get more growth per watt.

The other issue really is what coloration and aesthetics a particularly color spectral curve imparts to the plants. This is far harder to quantify(thus matters little in terms of growth itself), but PUR and RGR (Relative growth rates) can be quantified. This is particularly true when you get down closer and closer to where P=R, or the light compensation point for lower energy input for PUR.


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## Hoppy

It is also noted by some people who have measured PAR for their light, that bulbs with different color temperatures, 6500K and 10000K for example, produce different PAR. For now I think it is hard enough to characterize what a given light fixture produces in PAR vs distance, that the finer points, like color temperature, will just have to wait a few years. The difference in PAR from a 10000K and a 6500K bulb is probably within the uncertainty range for most lights. And, all of this data is from lights operated out in the air, not in a water filled tank, where the difference is also probably within the uncertainty range for most lights.

Tonight I was measuring PAR from a screw-in CFL bulb in a dome type reflector. I noticed that on turning on the light the PAR slowly increased for a minute or two, then even more slowly dropped part of the way back. It was an old bulb, so this may be a problem with the bulb's built in ballast. Imagine the error this could introduce if you didn't allow for it.


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## HolyAngel

Thank you for updating all this hoppy!! ⛄


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## sayurasem

Technology in aquarium has stepped up!
I still remember 2 years ago "watts per gallon" was still widely used.


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## Steve001

Hoppy said:


> PUR = photosynthetically usable radiation, a concept I haven't yet seen a good reason to dig into. Plants use light from the whole spectrum between about 400 and 700 nanometers wave length. Unlike what many people believe, they also use green light, just not as efficiently as they use blue and red light.
> 
> If it was hard to get enough light to grow our plants, we would want to get every advantage we could, and look for bulbs that wouldn't waste any light in the green wave lengths, which, if you think about it, would leave us with very drab looking plants. But, the bigger problem we now have is avoiding too much light, not getting enough light. So, why bother with PUR?


I know your position on PUR measurements, so my suggestion was only half serious. I think your charts are a good general guide because all manufacturers of lights fairly much use the same three phosphors, the caveat, but in varying proportions even though they have access to as many as 20 I believe.


Let me present this argument why I feel PUR is important. A PAR meter measures all PAR wavelengths. It's a generalist's tool. The charts you have created do not plot PAR wavelengths vs. micromol, they show total PAR wavelengths in micromols. As you noted plants use green light and likely other wavelengths less efficiently. But other wavelengths most efficiently. How does one determine from the charts what specific wavelengths of PAR you are actually measuring for any particular light source ? 
Knowing PUR vs. Distance could avoid this perhaps. 


> But, the bigger problem we now have is avoiding too much light, not getting enough light. So, why bother with PUR?




Aesthetics (CRI) is another matter for a separate discussion.


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## BruceF

Cost of dividing watts by gallons? Price less.


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## frrok

This is excellent info. I just wish more people of aware of this. Unfortunately a lot of people still go by "watts per gallon" some people think that the more "watts" they have the more "hi-tek" they are. They are very mid-informed.


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## Hoppy

Steve001 said:


> Aesthetics (CRI) is another matter for a separate discussion.


CRI remains a bit mysterious to me. Recently I read that incandescent light gives a CRI of 100 - perfect. That was because the color rendering index is designed so that perfect color rendering is that of incandescent light. I doubt that anyone reading this wants an aquarium to look like it has incandescent bulbs lighting it.

My first tank, back in the 1950's had an incandescent light, which I quickly replaced with a DIY T12 fluorescent light. I was amazed by how much better it looked with the fluorescent light, even though T12 bulbs, all that were available then, were notorious for making people look like ghouls.


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## Steve001

Hoppy said:


> CRI remains a bit mysterious to me. Recently I read that incandescent light gives a CRI of 100 - perfect. That was because the color rendering index is designed so that perfect color rendering is that of incandescent light. I doubt that anyone reading this wants an aquarium to look like it has incandescent bulbs lighting it.
> 
> My first tank, back in the 1950's had an incandescent light, which I quickly replaced with a DIY T12 fluorescent light. I was amazed by how much better it looked with the fluorescent light, even though T12 bulbs, all that were available then, were notorious for making people look like ghouls.


CRI is a complicate subject but worthy of aesthetic consideration. I feel the target light quality should bare a close semblance to *noon equator sunlight. Most people would probably agree since most people choose a light source of 6500k. 
With all the phosphors available for use, I wonder why lighting techs don't design a flourescent light source that has a better semblance to noon sunlight at the equator ? Thereby creating a light source with good PAR/PUR and good CRI. Perhaps it's just too costly for a small market.
Bulbs that have good CRI >90 are: 
*Giesmann* 6000k Midday 
*Eiko's* 5500K ColorMaster Digital bulb
*Alzo's* 5600K video bulb

*It seem to be around 5800K.


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## jcgd

I believe the issue is the cost/ difficulty of making a high cri bulb versus the people who actually care for/ need one. 

I believe a cri of 100 makes an object appear just as is would outside under the sun. I don't believe it matters too much for us, as we use whatever looks appealing to us.


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## bucilini

I'd recommend we "sticky" this tread.


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## Michiba54

Hoppy said:


> This is based on my own measurements, using brand new GE CFL 6500K bulbs, in 8.5 inch diameter reflectors. *Larger reflectors will give lower PAR and smaller will give higher PAR.*


Based on the threads I've read here the 8.5 dome lamp seems to be much more popular then samller one.

Is that because the 8.5 inch dome will give you a wider light spread then a 5 inch at the same distance?


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## BS87

Excellent post and thread. My only suggestion would be possibly lowering the scaling on the CFL chart. It goes very high, and most people using CFLs are intetested in a PAR range of 10-100 or so ( from what I can gather).


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## Geoscouter

Great information! What is missing is a graph on LEDs. Thanks for all the time you spent gathering this info and then sharing it with us. I didn't realize that a less than $100 par meter option existed


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## Hoppy

Michiba54 said:


> Based on the threads I've read here the 8.5 dome lamp seems to be much more popular then samller one.
> 
> Is that because the 8.5 inch dome will give you a wider light spread then a 5 inch at the same distance?


Yes, when the same amount of light is spread out over a larger area it has to be at a lower intensity, and vice versa.



BS87 said:


> Excellent post and thread. My only suggestion would be possibly lowering the scaling on the CFL chart. It goes very high, and most people using CFLs are intetested in a PAR range of 10-100 or so ( from what I can gather).


Good suggestion! I changed it.



Geoscouter said:


> Great information! What is missing is a graph on LEDs. Thanks for all the time you spent gathering this info and then sharing it with us. I didn't realize that a less than $100 par meter option existed


LED lights can't be treated this way. The variety of configurations is almost endless, so no simple charts can ever show much of value with them. However, it would be possible to put the most popular, most usable on planted tank ones on one chart. Keeping that chart up to date as more and more different LED lights become available would be a major chore. Maybe someone wants to convert the information in http://www.plantedtank.net/forums/showthread.php?t=160396 to this format? It takes a lot of time.


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## papaj10789

I would be really interested in seeing the figures on common LED fixtures or even single LED stars put into more common terms than the link provided for the led lighting compedium. The charts Hoppy has created for the different lights and brands is easily understood.


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## ThatGuyWithTheFish

Why do you consider 50 PAR to be high light? I've read somewhere else that they say 100 is high! Maybe they're using different units/measurements.


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## Michiba54

ThatGuyWithTheFish said:


> Why do you consider 50 PAR to be high light? I've read somewhere else that they say 100 is high! Maybe they're using different units/measurements.


PAR values are subject to change and based on the posters (Hoppy) experience... in this case Hoppy has a lot.

Another thing to consider is the PAR values are at the substrate, so if you have 50 PAR at the substrate you could easily have 150 at the water surface. 

Lastly, it has been said by many people that if you have 50PAR at the substrate there isn't a plant you can't grow with proper CO2 and ferts.


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## Hoppy

papaj10789 said:


> I would be really interested in seeing the figures on common LED fixtures or even single LED stars put into more common terms than the link provided for the led lighting compedium. The charts Hoppy has created for the different lights and brands is easily understood.


OK, I just spent most of the day making a chart as you requested. It is best used just to help filter out the LED lights that won't work for you. Once you do that you can do more research on those that look like they might work. See the first post for the chart.


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## kubalik

Hey Hoppy !
Would you happen to know how wide one of those finex ray 2 light fixtures would cover at 25" above the substrate ? For 18" wide tank I would need two of those to stay in medium-high light ?
Thx.

Btw , great job man , thanks a lot.


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## sayurasem

kubalik said:


> Hey Hoppy !
> Would you happen to know how wide one of those finex ray 2 light fixtures would cover at 25" above the substrate ? For 18" wide tank I would need two of those to stay in medium-high light ?
> Thx.
> 
> Btw , great job man , thanks a lot.


wide as in fixture wise... or the angle of light? These fixtures are pretty skinny.
These fixtures are only 2 3/4" wide. I do remember they use a 120 degrees lense over the leds.


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## kubalik

sayurasem said:


> wide as in fixture wise... or the angle of light? These fixtures are pretty skinny.
> These fixtures are only 2 3/4" wide. I do remember they use a 120 degrees lense over the leds.


Yeah I meant the angle of light , at 120 degrees I should be fine with one


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## Hoppy

Some of the LED light vendors put graphic charts showing the light spread on their websites, but I don't recall that Finnex does that.


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## teonguyen

Hi Hobby! Just a quick question and hope you can help me clarify on this. According to the chart for T5HO, At 21'' above the substrate the Catalina 4 bulbs give 80 micromols ; the Catalina 3 bulbs gives approx 62 micromols. Does this mean turn all bulbs on will give that certain PAR value or we multiply the PAR by number of bulbs ? Thank you


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## Hoppy

teonguyen said:


> Hi Hobby! Just a quick question and hope you can help me clarify on this. According to the chart for T5HO, At 21'' above the substrate the Catalina 4 bulbs give 80 micromols ; the Catalina 3 bulbs gives approx 62 micromols. Does this mean turn all bulbs on will give that certain PAR value or we multiply the PAR by number of bulbs ? Thank you


The PAR numbers in those charts are for the actual light fixtures, with a full complement of bulbs. The exceptions are the ATI 4 bulb fixture, which had only 3 bulbs in it, and the calculated PAR shown for one bulb for Tek and Catalina lights. That last one for the Tek lights is usable by multiplying the number of bulbs by the PAR per bulb. But, Catalina uses different shaped reflectors in various light fixtures, so the number is only good for those with similar reflectors (the one bulb Catalina lights appear to use the most different reflector shape.)


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## teonguyen

Hoppy said:


> The PAR numbers in those charts are for the actual light fixtures, with a full complement of bulbs. The exceptions are the ATI 4 bulb fixture, which had only 3 bulbs in it, and the calculated PAR shown for one bulb for Tek and Catalina lights. That last one for the Tek lights is usable by multiplying the number of bulbs by the PAR per bulb. But, Catalina uses different shaped reflectors in various light fixtures, so the number is only good for those with similar reflectors (the one bulb Catalina lights appear to use the most different reflector shape.)


This research is awesome and I think it s much more details than the previous charts. Thanks for your clarification..:thumbsup: and please keep us posted with your new studies.....


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## LetsTalkTanks

You said in your data for t8's that you were recording par readings on t8's with basic white reflectors. Aqua one has two 36" fixtures "flouro grow" and "al30d" (specifically speaking of the one I want). With "polished aluminum" reflectors which looks like it is one reflector spread out for two tubes. What would you recon The par would be with this in consideration as well as the new data collected from Thr diamond plated t8's.


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## Hoppy

I updated the chart for T8 lights with the latest data that sowNreap posted. That should let you make a good guess about what you would get with that Aqua one light.


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## Gafi

nevermind, answer was seen in earlier posts


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## Gafi

Acturally....I do have a questions now....if you put 2 fixtures that each give say 60 PAR....does that mnean you have 120 PAR in the water.....or does that mean you just have 2 60 PAR fixtures directing light into the tank? Looking for the best way to get high light in my 90 Gal Planted Tank


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## Hoppy

PAR isn't something that you put into the tank. It is the intensity of the light at various points in the tank. The light can come from room light and/or one, two, three, etc. lights sitting on top of, or hanging above the tank. When you have two lights close together, their light overlaps a lot, so the intensity can double right under the bulbs. But, if the two lights are widely spaced, say 8 inches apart, the overlap is mostly of the lower intensity area away from directly under the bulb, so the intensity in the middle of the tank is more likely to be about the same as when only one light is over that spot.

A 90 gallon tank is about 18 inches front to back, so it is helpful to have two lights, widely separated, to get more uniform light intensity over the whole substrate. If you put two light close together you will get possibly double the intensity right under the lights, but near the front and back of the tank the intensity will likely be much lower.

If you are sure you want high light, you can use a Catalina Aquarium 4 bulb T5HO, with the bulbs in two groups of 2 bulbs, with the groups about 8-10 inches apart, in an extra wide housing. That will be a custom light, but they have made some like that for other people.


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## Gafi

what are you thoughts on this lighting fixture Hoppy http://www.jlaquatics.com/product/s...Light+4+Bulb+T5+Fixture+(48+Inch,+4x54W).html

PS the issue with the Catalina ones, are I am not sure they ship to Canada and if they do, im sure it would be ridiculous


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## Hoppy

It would be worth a phone call to Catalina to find out what it costs to ship there. They have great customer service. The Tek light would really be a lot of light for a planted tank. Using two bulbs only would probably make it work, but with 4 bulbs you would need to hang it high above the tank.


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## bluestems

This is very helpful. Thanks, Hoppy!

ps- what does it mean if an LED specification states "Luminous intensity: 1400mcd or 17.60Lm per LED"


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## Hoppy

mcd is millacandela. http://www.ohmslawcalculator.com/mcd_to_lumens.php


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## acro12

*Led Par @ 35" depth*

Thank you Hoppy.Outstanding analysis.

So, if I'm understanding the led chart correctly then; 2-36" TrueLumen Pro fixtures will produce app 40 par at 35" depth ?
Thanks again,
Kim


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## Hoppy

acro12 said:


> Thank you Hoppy.Outstanding analysis.
> 
> So, if I'm understanding the led chart correctly then; 2-36" TrueLumen Pro fixtures will produce app 40 par at 35" depth ?
> Thanks again,
> Kim


That is correct, providing you space them at 2.75 inches apart. If you have them too far apart you only get half of that PAR - what one strip would give you. But, I don't know how far apart that would be - probably several inches. But, then you would get more uniform PAR over more of the front to back depth of the tank.


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## acro12

*truelumen*

Thanks Hoppy,

Trying to get a low light on a 220 gal semi planted discus set up.
tank 72x24x30h.

What you think using 4-36" for this kind of set up?


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## metallicanick78

having had a 220 with those dimentions and a odyessa 72" 4x80w fixture I can say I wish I had gone with 4 36" fixtures instead... Or at least 2 of their 72" fixtures. Light was excellent but only in a very limited swath under the fixture. Their 72" fixtures come with 3 switches, 2bulb 2bulb and led moons. Id just leave 2 bulbs off in each fixture for lower light. (or go for the afformentioned 4x36"ers)


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## Hoppy

I think tanks 18" or more in front to back depth will do better with two rows of widely spaced lights than one row of more intense light. So, I would use the 4 36 inch long lights, also because shipping 6 foot long lights and bulbs is more risky and expensive than shipping 36 inch long lights and bulbs.

However, if you hang the light a foot or more above the top of the tank, a single row of lights should work fine.


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## Gafi

Hey Hoppy

I was wondering for that 90 gal tank that I mentioned earlier....which of these planted ballasts from Catalina would work best?

2x54 W
http://www.catalinaaquarium.com/store/product_info.php?cPath=71_198_200&products_id=1842

1x54 W
http://www.catalinaaquarium.com/store/product_info.php?cPath=71_198_200&products_id=1837

3x 54 W
http://www.catalinaaquarium.com/store/product_info.php?cPath=71_198_200&products_id=1638

or do you suggest something different?


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## Hoppy

Gafi said:


> Hey Hoppy
> 
> I was wondering for that 90 gal tank that I mentioned earlier....which of these planted ballasts from Catalina would work best?
> 
> 2x54 W
> http://www.catalinaaquarium.com/store/product_info.php?cPath=71_198_200&products_id=1842
> 
> 1x54 W
> http://www.catalinaaquarium.com/store/product_info.php?cPath=71_198_200&products_id=1837
> 
> 3x 54 W
> http://www.catalinaaquarium.com/store/product_info.php?cPath=71_198_200&products_id=1638
> 
> or do you suggest something different?


As I pointed out earlier: http://www.plantedtank.net/forums/showpost.php?p=1974604&postcount=43 it depends on whether you want high light or something lower. For high light, phone Catalina and ask for a quote on the custom light I described. If you want less than high light, do you want low light, so you don't need CO2, or do you want high enough light to grow anything if you also use CO2?


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## Gafi

Hoppy said:


> As I pointed out earlier: http://www.plantedtank.net/forums/showpost.php?p=1974604&postcount=43 it depends on whether you want high light or something lower. For high light, phone Catalina and ask for a quote on the custom light I described. If you want less than high light, do you want low light, so you don't need CO2, or do you want high enough light to grow anything if you also use CO2?


I have been in contact with them, they are asking which hood I like etc etc etc.....what did you mention about the fixture width....was it 7inches between bulbs? I cant remember nor can I seem to fidn the post


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## Gafi

nevermind, didnt see the link in your reply....thanks!


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## Gafi

Gafi said:


> Hey Hoppy
> 
> I was wondering for that 90 gal tank that I mentioned earlier....which of these planted ballasts from Catalina would work best?
> 
> 2x54 W
> http://www.catalinaaquarium.com/store/product_info.php?cPath=71_198_200&products_id=1842
> 
> 1x54 W
> http://www.catalinaaquarium.com/store/product_info.php?cPath=71_198_200&products_id=1837
> 
> 3x 54 W
> http://www.catalinaaquarium.com/store/product_info.php?cPath=71_198_200&products_id=1638
> 
> or do you suggest something different?



would any of these classify as medium lighting? I'd prefer to avoid the custom order route as them sending it to Canada seems to increase the cost significantly over their prebuilt models.


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## Hoppy

You can hang a multi bulb light high above a 90 gallon tank and get medium light. See the charts in the first post here.


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## parrottbay

Hoppy,

I am still having problems understanding all of this....Is there a simple one that states something a little bit easier to understand?


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## Hoppy

It is a bit complicated, no question, but I don't know how to simplify it any more.


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## Jnad

*Cfl vs t5*

Hello!

Am i reading the measured par charts in the first post of this tread right?

Is 23w cfl vertically mounted in a reflector giving more par than a Hagen Glo 2xT5?

I am setting up an ADA tank with dimensions 75x45x45cm, i do have a Hagen Glo 2x24 T5 that i can use, but when reading the par charts it seems to me that two reflectors (diameter 25cm) with 23W cfl will probably give better par than my Hagen Glo. Maybe also give better spread of the light beacuse the Hagen Glo fixture only have one reflector, both T5 tubes are placed under one reflector.

Do i reading the par chart right?

And when using a cfl with reflector, Does the reflector have to be shining aluminium color or is a white painted reflector ok?

Jnad


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## Hoppy

Yes, you are reading the charts right. A 23 watt screw-in CFL bulb in a 10.5 inch diameter dome reflector, polished aluminum suface, gives considerably more PAR than the Hagen Glo 2 bulb light. But, the Hagen Glo light covers more area with that light - it would take two of the CFL bulb/reflectors to cover the same area.

I don't know if anyone has measured PAR with those dome reflectors with white painted inside surfaces. I doubt that they would do nearly as good as the aluminum surface reflectors. Aluminum is inherently a very good reflector even if not well polished.

We have had some problems duplicating PAR measurements with CFL bulbs, especially when the bulbs extend slightly beyond the spherical surface of the reflector, so don't rely too much on the charts for them.


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## Gafi

Just have a question about the Sunlight Tek lights in the chart Hoppy. You mention that the Tek lights PAR value is 1 bulb calculated....does that refer to this particular unit....have you measured the PAR in this unit in particular? Any thoughts?

http://www.jlaquatics.com/product/s...Light+4+Bulb+T5+Fixture+(48+Inch,+4x54W).html


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## Jnad

Tanks



Hoppy said:


> Yes, you are reading the charts right. A 23 watt screw-in CFL bulb in a 10.5 inch diameter dome reflector, polished aluminum suface, gives considerably more PAR than the Hagen Glo 2 bulb light. But, the Hagen Glo light covers more area with that light - it would take two of the CFL bulb/reflectors to cover the same area.
> 
> I don't know if anyone has measured PAR with those dome reflectors with white painted inside surfaces. I doubt that they would do nearly as good as the aluminum surface reflectors. Aluminum is inherently a very good reflector even if not well polished.
> 
> We have had some problems duplicating PAR measurements with CFL bulbs, especially when the bulbs extend slightly beyond the spherical surface of the reflector, so don't rely too much on the charts for them.


----------



## Jnad

Hoppy said:


> Yes, you are reading the charts right. A 23 watt screw-in CFL bulb in a 10.5 inch diameter dome reflector, polished aluminum suface, gives considerably more PAR than the Hagen Glo 2 bulb light. But, the Hagen Glo light covers more area with that light - it would take two of the CFL bulb/reflectors to cover the same area.


Does this mean that cfl bulbs actually is more effective than T5 lightning when used in the right fixtures? 

Jnad


----------



## toffee

Jnad said:


> Does this mean that cfl bulbs actually is more effective than T5 lightning when used in the right fixtures?
> 
> Jnad


Not sure about that but I did use couple of 40w CFL with 10" (or was it 12") round reflectors, on my 180g. Not to light the whole tank but rather as spot light to grow plants right underneath them. Almost too much light, end up with swords almost 30" tall. 

I did make the mistake of placing the cfl and reflector too close to the top of acrylic tank. After a few months, the top was slightly deformed.


----------



## Jjensen187

I just set up a 14watt 5k CFL with a aluminum dome reflector over my 10g for my plants. Its about 14" from the substrate. I'm trying to grow crypts, java fern, and micro swords. I plan to add dwarf hairgrass in the near future. Should I install another lamp over my tank? I want low-med lighting. Dosing Flourish once a week, and 1ml of API co2 daily.

Im confused because the PAR chart in this thread doesnt match one in another.


----------



## Hoppy

This thread supersedes the earlier one, as noted in the first post in that older thread (bold type).

The dome reflectors can't cover a 20 inch long tank with light, so it takes two of them to get good coverage.

It is still up in the air whether the charts for CFL bulbs in those dome reflector are correct. I suspect that they are good, and that we have misused our lux meters in getting later data. This will be worked out eventually.


----------



## Gafi

Gafi said:


> Just have a question about the Sunlight Tek lights in the chart Hoppy. You mention that the Tek lights PAR value is 1 bulb calculated....does that refer to this particular unit....have you measured the PAR in this unit in particular? Any thoughts?
> 
> http://www.jlaquatics.com/product/s...Light+4+Bulb+T5+Fixture+(48+Inch,+4x54W).html


If i were to hang this fixture about 12 inches off my 90 gallon tAnk....by your estimation hoppy would this be medium light at the substrate and high light at the top of the tank?


----------



## In.a.Box

If I were to use 1 dual HD DP shop light with 2 6500k bulb on my 75G I would get about just close to 45 PAR hanging my light 25 inch from the bottom? How width will the HD shop light cover(front to back)? Im aiming at Med Light.


----------



## Hoppy

In.a.Box said:


> If I were to use 1 dual HD DP shop light with 2 6500k bulb on my 75G I would get about just close to 45 PAR hanging my light 25 inch from the bottom? How width will the HD shop light cover(front to back)? Im aiming at Med Light.


I think you will get around 45 PAR, but there will be some drop off in PAR near the front and back glass. That tank is about 18 inches front to back, so ideally you would use two lights.


----------



## In.a.Box

Thanks hobby,

Has anyone use chrome aluminum paint inside a cheap $10 shop light?


----------



## jdmstop

Hoppy,

Which model of 24" ray 2 did you use for the par test? Was is the 7000k, 192 led model? So if I mount this on top of my 14" tall tank with a 2-3 inch substrate, I will be getting about 80-95 par? 

Thank you for all your efforts into the research! 


Sent from my iPad using Tapatalk HD


----------



## Hoppy

The data for the Finnex lights is from http://www.plantedtank.net/forums/showthread.php?t=189944


----------



## Rokuzachi

Just wanted to say that this thread is amazing and thanks for all the data. It's gone a long ways in helping me understand the lighting situation in my tanks and has greatly aided me in finding the _correct_ lighting solutions. Well, correct being what I'm after, which is certainly not where the WPG rule led me when I set the tanks up a while back.

I'm currently putting together a brand new 100g planted setup for my beloved catfish. It should be a much more enjoyable experience with the right lighting


----------



## tylergvolk

I have 2 questions that I wold like to address. One the them everyone could benefit from and the other question is more specific to my setup.

I have a coralife 36" T5HO fixutre with 2 39w bulbs
1. 6,700K BULB
2. Colormax BULB

I currently have the fixture lifted 15 inches from the substrate which is about 40PAR; however, I read somewhere that the colormax bulbs don't provide as much PAR value as the regular 6,700K would. Is this true? Has anyone tested the colormax PAR values?

I also have a recessed canister in my ceiling that give off light to this tank. It is a single LED 13w 800lumes bulb about 32" from the substrate at the front of my tank. My question is, how much will this effect my PAR?


----------



## Hoppy

Someone can contribute information if they have the two bulbs and a PAR or lux meter. Just take light readings at various distances from the light, and report the readings here. Without that data one can only guess whether the two bulbs produce about the same PAR.


----------



## tylergvolk

tylergvolk said:


> I have 2 questions that I wold like to address. One the them everyone could benefit from and the other question is more specific to my setup.
> 
> I have a coralife 36" T5HO fixutre with 2 39w bulbs
> 1. 6,700K BULB
> 2. Colormax BULB
> 
> I currently have the fixture lifted 15 inches from the substrate which is about 40PAR; however, I read somewhere that the colormax bulbs don't provide as much PAR value as the regular 6,700K would. Is this true? Has anyone tested the colormax PAR values?
> 
> I also have a recessed canister in my ceiling that give off light to this tank. It is a single LED 13w 800lumes bulb about 32" from the substrate at the front of my tank. My question is, how much will this effect my PAR?



Read post number 61 & 66 from the following link:

http://www.aquaticplantcentral.com/...c-plant-club/80982-par-data-collection-7.html

I wonder if this information is credible...


----------



## Amandas tank

I just finished reading through this thread and I want to thank you Hoppy and all those that have contributed. Now, if only I can wrap my mind around this and make sense of it I'd be well on my way 

My tank is 48" x 18" x 24". Right now I have two 48" T8 bulbs that say nothing on them other than they are 40 watts each. They are pink and came with the tank (bought off craigslist). I also have two 36" T5 bulbs on the front side of the tank. Both are 39 watts one being 6500K and the other 10000K. I have no clue the PAR rating of any of them. I am concidering just starting over with new lights all together choosing something from the charts you have provided so the PAR is already pointed out for me. I do not use Co2 and don't plan to start. So, I definetely need to stick with low light.

If anyone of you reading this have a tank similar to mine without Co2, and your plants are doing great, please share with me what you are using. Hoppy, if you have a recommendation, I'd greatly appreciate it! 

Thank you for your time and effort you've put into this thread and helping those of us that are at a loss in the lighting side of the hobby.


----------



## Gold Finger

Am in a similar situation as Amanda's Tank. Have four T8's on top of my 24"tall 80 gallon tank. It should be low light at ~40umol, I guess. I want to go up to medium at ~55umol since adding excel and ferts. Will be looking to get a double T5HO fixture with poor reflector and rest it right on top. No real question here. Thank to Hoppy, all my answers are out there.


----------



## Sluggo

Overwhelmed with info here. Looking to light a 38-gal with low-medium light. Tank is 20"H x 36"L x 12"W. I have a Coralife 2x96w PC fixture on hand, but the fan is noisy. There is a Current 3x39w T5HO available that is very affordable. Or, am I better off with something from Home Depot?


----------



## Hoppy

tylergvolk said:


> Read post number 61 & 66 from the following link:
> 
> http://www.aquaticplantcentral.com/...c-plant-club/80982-par-data-collection-7.html
> 
> I wonder if this information is credible...


It would be interesting for someone to go through that whole thread and compile the data by manufacturer's lights. For example, I don't have any good data for the Coralife PC lights, and I noticed that there is some there, which supports my opinion that those lights are very poor ones.


----------



## switch26

I see the Aquatic Life 36'' T5HO fixture, but I have 2 bulbs instead of 4..

2, 39w bulbs, one 6000k and the other is a 650nm roseate, im thinking of replacing with 2 6500k bulbs for better plant growth..

Anyway, can anyone tell me what my readings would be for that fixture currently? I have a 30 gallon tank and my fixture is about 16 inches from my soil?


----------



## Hoppy

switch26 said:


> I see the Aquatic Life 36'' T5HO fixture, but I have 2 bulbs instead of 4..
> 
> 2, 39w bulbs, one 6000k and the other is a 650nm roseate, im thinking of replacing with 2 6500k bulbs for better plant growth..
> 
> Anyway, can anyone tell me what my readings would be for that fixture currently? I have a 30 gallon tank and my fixture is about 16 inches from my soil?


You should get about 70-75 micromols of PAR with that light, which I consider to be high light.


----------



## switch26

Thank you hoppy. Would that be the same even with the stock bulbs that I listed? Or if i got 2 new 39w 6500K bulbs?

Reason being is my growth is significantly slower with the stock bulbs than before when i used 2 flat coral life fixtures with very poor reflectors.

Although it was still 4 bulbs. and they were 6500k each, not HO


----------



## jabba

Tank: 55 gallon, 19 inch tall
Lights: 2x Hagen Power-Glo T5HO 18,000k, 2150 lumens, 233 lux
Light Distance: 24 inch

Ok from what I've read so far, I should be under 40 par. I couldn't find anyone with a par reader for me to measure so I was hoping anyone can confirm this? I was planning to move it up by 12 inches from the top but I'm afraid of losing too much par.

What kind of bulbs was used to test out the Hagen lights were used? was it the 6500k or the 18000k or it doesn't matter, all 54w are the same? I was hoping to achieve around 50 par but I guess it won't be possible unless I want to dish out money for new lights.


----------



## Hoppy

Those charts will give you approximate values for the PAR at the substrate, but if you want to really know what PAR you have with your tank and your bulbs and your light fixture, you have to measure it with a PAR meter.

There is still a lot to be learned, and probably un-learned about various lighting options. For example, what is the effect on PAR using various color temperature bulbs, or bulbs from various manufacturers, or year old bulbs vs new bulbs, etc. Also, do plants really respond the same to 50 micromols of PAR from a LED light made with cool white LEDs and one made with a mix of different colors? Any one with a PAR meter and enough interest can contribute a lot to our knowledge.


----------



## AUvet14

I have a GLA 36-L, same size as ADA Mini M, on the way. I am considering lighting options for it. I do plan to run CO2 with ferts. I am aiming for "high light". The fixtures I have pretty much narrowed it down to are the Archaea 27W Power Compact fixture and the 16'' Finnex Ray 2 DD LED fixture. Considering the size of the tank and what I want to grow (probably HC or glosso carpet and potentially some red stems), would both of these fixtures likely be sufficient?


----------



## thegr8wendt

*Is a watt a watt regardless of the source?*

Compare (2) 90 watt LED fixtures (180 watt total) to a hybrid fixture with (1) 150 watt Metal Halide & (1) 39 watt PC. (190 watts total). Will it actually cost less to run the LED lamps as opposed to the hybrid fixture with Metal Halide & PC lamps? Or is a watt a watt regardless of the source?


----------



## kyleax1

I have a 55 gallon tank and have 48" Nova Extreme 2xT5HO. When I bought it I thought I was getting the recommended light for medium light plants (2 wpg).

After continually fighting algae I started looking for answers and found that based on your par info that these are most likely considered high light for my tank.

I wanted to take one bulb out, but then realized it only works if I have 2 bulbs in.
If I take window screen and put a layer of it inside the light on the plastic slide out splash guard will that reduce the light enough to help keep the algae down but still be enough for all my plants on the bottom? The screen won't melt/burn will it?

I have dwarf sag that is finally starting to spread, but I'm sick of clipping bba and hair algae every day. I've already reduced my light period to 6 hours a day and its slowed down the algae, but has not stopped it.

I use diy co2, don't want pressurized co2 and is seachem fert dosing chart, but am soon hoping to switch to pps pro.


----------



## hsilive

ok here we go i used to grow pot i dont know bout all these numbers and what not but here is my break down 

hpsv and mh lights had 6 ft growable light spec 
floresents only 3 to 6 inches 
led i only used for clones and it streched the plants alot 

you do need a full spectrum of lights to grow in fact dif specs will help plants grow in different ways such as in pot with veggie growth and flowering 
i will expiement with my new fluval 12g tank for us i think water helps increase the usable light kinda like a tin can phone works with sound so for my 12 i will use stock lights plus about 60 watts soft white led and 30 of uv trust me uv does help maybe will kill some algae too ! this is a tall tank and thats part of why im going overkill and if it dont work i will get a high pressure sodium vapor and a metal holide and try that ! just hoping between the blues whites and uv i will have a good mix and maybe with those watts hit the bottom of the tank !!


----------



## accordztech

Hoppy, have you ever put together the data that we collected at the last meeting?


----------



## bradlgt21

So since the 4 bulb aquaticlife fixture is about 90 Par at 25" would it be safe to say the 2 bulb version would be about 45 par at 25"? Is this the fixture tested?

AquaticLife T5 HO Dual Lamp Light Fixtures


----------



## jonathan

I wonder if there is a way to convert a photography light meter reading to par...


----------



## mcarroll

A photography meter is probably reading in LUX. If so...

One answer is that "no" you can't convert from LUX to PAR with a standard conversion.

Another is that "yes" you can convert as long as you know the same bulb's PAR index. (I.e. someone else has taken both a PAR and LUX reading of the same bulb you are using and created a conversion factor from these measurements.)

There's a wide variety of "color profiles" in bulbs, and this can have a big impact on the actual PAR you calculate. Having said that, if you know for a fact that one of the index bulbs has a similar color profile to your bulb, then you can still get some idea of your PAR from the calculation.

If you search, I think Advanced Aquarist has some index values listed somewhere.

I'm using a LUX meter as well...I think it you're aware of how it works and the limits involved you can make due pretty well without worring about PAR. (OTOH, if you can borrow a PAR meter though...)

-Matt


----------



## mcarroll

jabba said:


> Tank: 55 gallon, 19 inch tall
> Lights: 2x Hagen Power-Glo T5HO 18,000k, 2150 lumens, 233 lux
> Light Distance: 24 inch
> 
> Ok from what I've read so far, I should be under 40 par. I couldn't find anyone with a par reader for me to measure so I was hoping anyone can confirm this? I was planning to move it up by 12 inches from the top but I'm afraid of losing too much par.


To the degree you are confident of your current numbers, a bit of math should give you a workable number for your hypothetical setup.

As your space between the light and water surface doubles, the light intensity will be only 1/4 of what it was. Going the other way, you can quadruple your intensity by reducing the light's distance to the water by 50%.

You could expect a commensurate quartering (or quadrupling) of your value at the tank bottom.

(Effects are considerably more complex and severe when the water depth changes.)

-Matt


----------



## hsilive

wow i feel left out


----------



## Hoppy

accordztech said:


> Hoppy, have you ever put together the data that we collected at the last meeting?


I did something with it, but I'm not sure what. I think I added some data for the LED light we tested. That was a long time ago :smile:


----------



## Hoppy

bradlgt21 said:


> So since the 4 bulb aquaticlife fixture is about 90 Par at 25" would it be safe to say the 2 bulb version would be about 45 par at 25"? Is this the fixture tested?
> 
> AquaticLife T5 HO Dual Lamp Light Fixtures


That should be a good guess. I don't think I have any other data for Aquaticlife fixtures.


----------



## Hoppy

mcarroll said:


> A photography meter is probably reading in LUX. If so...
> 
> One answer is that "no" you can't convert from LUX to PAR with a standard conversion.
> 
> Another is that "yes" you can convert as long as you know the same bulb's PAR index. (I.e. someone else has taken both a PAR and LUX reading of the same bulb you are using and created a conversion factor from these measurements.)
> 
> There's a wide variety of "color profiles" in bulbs, and this can have a big impact on the actual PAR you calculate. Having said that, if you know for a fact that one of the index bulbs has a similar color profile to your bulb, then you can still get some idea of your PAR from the calculation.
> 
> If you search, I think Advanced Aquarist has some index values listed somewhere.
> 
> I'm using a LUX meter as well...I think it you're aware of how it works and the limits involved you can make due pretty well without worring about PAR. (OTOH, if you can borrow a PAR meter though...)
> 
> -Matt


As long as you are working only with fluorescent bulbs, with color temperatures between about 6500K and 10,000K, you can divide the lux reading by 76 and get reasonably close to the PAR value. Lights with more red or near UV in their spectrum can't be estimated with the same constant. The Lux meter is measuring a very small band of the spectrum compared to the PAR spectral range. (Sunlight also requires a different constant to convert from lux to PAR.)


----------



## Yankee

Hi I was looking at your LED chart and it says "Finnex Ray II DX". I can't find this fixture. Is this supposed to be the DS with 7000K LEDS? If so I think this is going to be a great option for me - at 24" this fixture is putting out high par ratings and is right in my budget.


----------



## Hoppy

Yankee said:


> Hi I was looking at your LED chart and it says "Finnex Ray II DX". I can't find this fixture. Is this supposed to be the DS with 7000K LEDS? If so I think this is going to be a great option for me - at 24" this fixture is putting out high par ratings and is right in my budget.


http://www.plantedtank.net/forums/showthread.php?t=189944 is the most up to date data on Finnex lights.


----------



## Yankee

Hoppy said:


> http://www.plantedtank.net/forums/showthread.php?t=189944 is the most up to date data on Finnex lights.


Thanks a lot, very informative! How up to date are the "high light" par parameters? I know the numbers are generally arbitrary but recently I've seen 80-120 par being labeled high. Would 50 par be capable of growing light demanding plants? I.e. dwarf baby tears.


----------



## Hoppy

Yankee said:


> Thanks a lot, very informative! How up to date are the "high light" par parameters? I know the numbers are generally arbitrary but recently I've seen 80-120 par being labeled high. Would 50 par be capable of growing light demanding plants? I.e. dwarf baby tears.


Because there is no widely accepted definition of "low", "medium" and "high" light, we can set our own definition if we want to. I like the idea that "low" means enough to grow many plants, and CO2 isn't at all necessary. "Medium" is enough to grow a very large variety of plants, with CO2 being highly recommended, and necessary for many of those plants, but the CO2 concentration doesn't need to be near the maximum the fish will tolerate. "High" is everything above "medium", and the CO2 concentration needs to be near the maximum the fish tolerate. (Plus, for both medium and, especially high light tank maintenance and setup need to be done very thoroughly and well to avoid algae problems.) Based on that I like 20-35 micromols of PAR as "low" light, 40-50 or 60 as "medium" light, and above that as "high" light. I don't have any argument with those who think different levels are more appropriate - they may be.

HC can be grown with 50-60 micromols of PAR as long as you use a good CO2 concentration too.

Remember, the PAR numbers are those at the substrate level in the middle portion of the tank. The actual PAR in the tank varies, being higher nearer to the water surface, lower in areas away from the middle portion of the tank and in shaded areas. The actual PAR at the plant leaves needed to grow a plant well is another subject.


----------



## Yankee

Hoppy said:


> Because there is no widely accepted definition of "low", "medium" and "high" light, we can set our own definition if we want to. I like the idea that "low" means enough to grow many plants, and CO2 isn't at all necessary. "Medium" is enough to grow a very large variety of plants, with CO2 being highly recommended, and necessary for many of those plants, but the CO2 concentration doesn't need to be near the maximum the fish will tolerate. "High" is everything above "medium", and the CO2 concentration needs to be near the maximum the fish tolerate. (Plus, for both medium and, especially high light tank maintenance and setup need to be done very thoroughly and well to avoid algae problems.) Based on that I like 20-35 micromols of PAR as "low" light, 40-50 or 60 as "medium" light, and above that as "high" light. I don't have any argument with those who think different levels are more appropriate - they may be.
> 
> HC can be grown with 50-60 micromols of PAR as long as you use a good CO2 concentration too.
> 
> Remember, the PAR numbers are those at the substrate level in the middle portion of the tank. The actual PAR in the tank varies, being higher nearer to the water surface, lower in areas away from the middle portion of the tank and in shaded areas. The actual PAR at the plant leaves needed to grow a plant well is another subject.


Great, thanks a lot! I'm thinking now I will run 2 2x54w aquatic life t5's to get me well over the recommendations. Thank you again, very informative article and recommendations.


----------



## Troxey

Another Aquaticlife question. The dual-lamp freshwater fixtures ship with a 6K bulb and a roseate bulb. Would removing the roseate and replacing with another 6K or 10K bulb affect the PAR value either way?


----------



## Hoppy

Troxey said:


> Another Aquaticlife question. The dual-lamp freshwater fixtures ship with a 6K bulb and a roseate bulb. Would removing the roseate and replacing with another 6K or 10K bulb affect the PAR value either way?


I don't recall if anyone has reported on the PAR from one of those roseate bulbs or not. Without that information I don't see how we can know.


----------



## Switch

Troxey said:


> Another Aquaticlife question. The dual-lamp freshwater fixtures ship with a 6K bulb and a roseate bulb. Would removing the roseate and replacing with another 6K or 10K bulb affect the PAR value either way?


I'm having exactly the same doubts... Specially cause the mixtures of bulbs seems to be less intense then with 2 6k bulbs... On the other hand the roseate is supposed to work on a more appropriate wavelengh for photosynthesis. Would be cool to figure how this balances out... Hoppy!! Can the roseate bulb be less intense to the human eye, compared with a 6k bulb, but have the same strengh in par usable by the plants??


----------



## Hoppy

Switch said:


> I'm having exactly the same doubts... Specially cause the mixtures of bulbs seems to be less intense then with 2 6k bulbs... On the other hand the roseate is supposed to work on a more appropriate wavelengh for photosynthesis. Would be cool to figure how this balances out... Hoppy!! Can the roseate bulb be less intense to the human eye, compared with a 6k bulb, but have the same strengh in par usable by the plants??


Assuming the roseate bulb produces a lot more red than the 6500K bulbs, it will look much dimmer, at the same PAR, than the 6500K bulbs. Our eyes are not very sensitive to red light, but very sensitive to green and yellow light.


----------



## Switch

Hoppy sir!!! Have another question for you... How do u think that surface agitation will influence the effect of par at the bottom of the tank??


----------



## Hoppy

Switch said:


> Hoppy sir!!! Have another question for you... How do u think that surface agitation will influence the effect of par at the bottom of the tank??


I haven't yet tested the effect of surface ripple on PAR, but I see no reason why it would have any significant effect. It might even slightly raise the PAR.


----------



## Switch

Thanks for quick reply!! Can u please elaborate a bit on why u think that?? But dont go too crazy...


----------



## funkman262

I apologize if this has already been answered, but I'm a little confused by the graphs. Are the Home Depot 2-bulb T8 fixtures really better than most of the 2-bulb T5HO fixtures in the graph above it?


----------



## Hoppy

Switch said:


> Thanks for quick reply!! Can u please elaborate a bit on why u think that?? But dont go too crazy...


Light reflects off the water surface in increasing amounts as the angle between the vertical and the light increases - at 0 degrees, straight down into the water, virtually no light is reflected, but at 90 degrees, parallel to the water, or close to it, most of the light is reflected. When the surface is rippled, a lot of the surface is at lower angles to the incident light even way off to the side from the light. So, that might lead to a higher PAR. But, I haven't tested this idea.


----------



## Hoppy

funkman262 said:


> I apologize if this has already been answered, but I'm a little confused by the graphs. Are the Home Depot 2-bulb T8 fixtures really better than most of the 2-bulb T5HO fixtures in the graph above it?


The chart shows that the diamond plate, 2 bulb, T8, Home Depot shop light gives about 70-75 micromols of PAR at 15 inches. The other chart, of T5 lights, shows only the Hagen Glo, Coralife and FishNeedIt 2 bulb T5HO lights give less than that, and those may have sub-standard ballasts, and do have relatively poor reflectors. I agree that it is hard to believe that the Home Depot T8 light is that good, but someone tested it and that was where the data came from. I also measured the PAR at one distance for one, at a local aquatic plant club meeting, and the reading was consistent with that chart. I saw one on a tank once, and it certainly did look very bright.


----------



## raulfd4

Two questions:

According to the PAR vs Distance for Various T5 Light Fixtures chart on the first page, the AquaticLife T5HO 36" 4 bulb fixture has about 90 PAR at 25 inches.

*Is it safe to assume that the same fixture with 2 bulbs has about 45 PAR at 25 inches?*

I have glass covers on top of my tank and they build up quite a bit of condensation.

*How much will the glass/condensation on the covers reduce the PAR of a light? *


----------



## Hoppy

raulfd4 said:


> Two questions:
> 
> According to the PAR vs Distance for Various T5 Light Fixtures chart on the first page, the AquaticLife T5HO 36" 4 bulb fixture has about 90 PAR at 25 inches.
> 
> *Is it safe to assume that the same fixture with 2 bulbs has about 45 PAR at 25 inches?*
> 
> I have glass covers on top of my tank and they build up quite a bit of condensation.
> 
> *How much will the glass/condensation on the covers reduce the PAR of a light? *


That is a safe assumption, that you would get half the PAR with half the number of bulbs.

The condensation on the underside of the cover glass should not appreciably reduce the PAR, but the hard water deposits it may leave behind will reduce the PAR. You need to keep the glass as clean as you can if you want to get the full PAR from the light.


----------



## GDominy

Hoppy said:


> Light reflects off the water surface in increasing amounts as the angle between the vertical and the light increases - at 0 degrees, straight down into the water, virtually no light is reflected, but at 90 degrees, parallel to the water, or close to it, most of the light is reflected. When the surface is rippled, a lot of the surface is at lower angles to the incident light even way off to the side from the light. So, that might lead to a higher PAR. But, I haven't tested this idea.


On my former reef tank I actually measured my par using an apogee meter with still water and aggressive surface movement. At a depth of 24" I would measure approximately 350 uMol with still water but during aggressive surface aggitation it would fluctuate between 345-355. From a practical standpoint it averages out and wasn't something I was concerned with.

For reference this was with 108 leds and 16 x 39 watt t5s over a 265 gallon tank. These results may not scale well with less intensity.


----------



## Hoppy

GDominy said:


> On my former reef tank I actually measured my par using an apogee meter with still water and aggressive surface movement. At a depth of 24" I would measure approximately 350 uMol with still water but during aggressive surface aggitation it would fluctuate between 345-355. From a practical standpoint it averages out and wasn't something I was concerned with.
> 
> For reference this was with 108 leds and 16 x 39 watt t5s over a 265 gallon tank. These results may not scale well with less intensity.


Thank you! That is very good to know. And, it is about what I thought would happen.


----------



## gozzy

*Hagen Glo T5 Questions.....*

Hi I've been looking at the charts and info on here so first of all thanks for all the good information  

I have a Hagen Glo T5HO Lighting and have in there 1 x Dennerle Trocal T5 Longlife Special Plant + 1 Color Plus bulb.

I've only realised after reading this thread they are not HO bulbs but LO (i think) :-(

My tank size is 12" in height and judging by the chart if the light unit is sitting on top of the tank this will give me around 65 par? The chart doesn't say whether these are for HO or NO bulbs though?

Can someone tell me the best use for this fixture in terms of bulbs and height from substrate please? I am looking to be in the high light category.


----------



## Bronco

*30 inch tank question*

Hoppy thanks for taking the time to post this information. 
Up until now I had been equating wattage with light intensity. 
A mistake that would have cost me a lot of extra money that 
I don't have. I just purchased a 30 inch tank so it falls into that 
odd size bucket. I plan on using C02 and would like high light. 
Would I better off using 2 aquatic life 2 bulb fixtures or just 
get a 6 bulb Catalina fixture and hang it a little higher above the tank 
to provide better coverage ? Thanks again for the informative post


----------



## Bronco

Sorry the tank is 24 inches deep


----------



## Hoppy

I'm not sure which light would be "best" for a high light 30 inch long tank. It depends a little on the front to back depth of the tank. If the tank is 12-14 inches front to back, a single light fixture should cover the substrate pretty well, but if it is 18" and more, I think two lights, or a single light, with two groups of two bulbs, with 7-9 inches between groups might work better. Or, if you want to hang the light above the tank, you could use a 24 inch long light with 4 bulbs. Then, there is always the LED option, too. You could also use a 4 bulb light, with two electric cords, and run the two front bulbs for half the photoperiod and the two back bulbs for the other half.


----------



## Bronco

Hoppy thanks for getting back to me. Sorry I just should
have given the complete dimensions of the tank right off
the bat. It's a cube that measures 30x30x24 so the light
will have to provide a lot of coverage. With this in mind would
any of the options you gave me for going the t5 route be
more favorable ?


----------



## Hoppy

A 30" x 30" footprint tank has to either use a light hanging high above the tank or a pair of lights sitting on the tank to get good coverage of the whole tank. That is a personal preference - you may like the appearance of a hanging light better, or want a light sitting on the glass top of a tank.


----------



## Bronco

Hoppy thanks again for the information


----------



## gozzy

*Hagen Glo T5 Questions.....*

Hi Hoppy 

Could you take a look at my question a few posts back titled "*Hagen Glo T5 Questions.....* " please?

My tank size is 60cm x 30cm x 30cm.

Thanks


----------



## Hoppy

gozzy said:


> Hi I've been looking at the charts and info on here so first of all thanks for all the good information
> 
> I have a Hagen Glo T5HO Lighting and have in there 1 x Dennerle Trocal T5 Longlife Special Plant + 1 Color Plus bulb.
> 
> I've only realised after reading this thread they are not HO bulbs but LO (i think) :-(
> 
> My tank size is 12" in height and judging by the chart if the light unit is sitting on top of the tank this will give me around 65 par? The chart doesn't say whether these are for HO or NO bulbs though?
> 
> Can someone tell me the best use for this fixture in terms of bulbs and height from substrate please? I am looking to be in the high light category.


Hagen Glo lights are T5HO lights, but with poor ballasts and just fair reflectors. You should get high light if it is mounted less than 16 inches from the substrate.


----------



## fishyjoe24

so according to this I would only get medium lighting with a coral-life t5 ho 2 bulb on a 27 cube 20x18x20 is this correct?


----------



## Hoppy

fishyjoe24 said:


> so according to this I would only get medium lighting with a coral-life t5 ho 2 bulb on a 27 cube 20x18x20 is this correct?


That tank is only 20 inches long, so I assume you would use a 20 inch long light. I don't know anything about a Coralife 2 bulb T5HO 20 inch light, but it will give you less than 30 miicromols of PAR, which is low light. If the bulbs or ballast are worse than usual for Coralife, it might be as low as 20 micromols.


----------



## fishyjoe24

Hoppy said:


> That tank is only 20 inches long, so I assume you would use a 20 inch long light. I don't know anything about a Coralife 2 bulb T5HO 20 inch light, but it will give you less than 30 miicromols of PAR, which is low light. If the bulbs or ballast are worse than usual for Coralife, it might be as low as 20 micromols.


boo. might have to do a retro fit with some tek reflectors and gisemenn bulbs then.

or would this get me up to med high/high light. the aqua life will one work or will I need too.
http://www.marinedepot.com/AquaticL...xtures-AquaticLife-AK01142-FILTFIT54U-vi.html


----------



## ThatGuyWithTheFish

What do you mean by Catalina 1 bulb calculated? What wattage is it?


----------



## Hoppy

fishyjoe24 said:


> boo. might have to do a retro fit with some tek reflectors and gisemenn bulbs then.
> 
> or would this get me up to med high/high light. the aqua life will one work or will I need too.
> http://www.marinedepot.com/AquaticL...xtures-AquaticLife-AK01142-FILTFIT54U-vi.html


This is just a little better than a guess: I think you would get around 50-60 micromols of PAR right under that light. But, it would take two of them, one near the front and one near the back, to get good light coverage of the whole tank. That would be medium light or a bit more.


----------



## Hoppy

ThatGuyWithTheFish said:


> What do you mean by Catalina 1 bulb calculated? What wattage is it?


That should hold for 3-6 foot long bulbs, and possibly even for 2 foot long bulbs. The problem with guessing how much light one of the Catalina fixtures gives you is that they use more than one shape of reflector. Unless we have actual PAR data for the specific light you are interested in, this is just a crude estimate.


----------



## ThatGuyWithTheFish

I ask because I think my 30" 1 bulb T5HO might not be enough.


----------



## hiyabrad

Hi Hoppy.

I am new here, this being my first post! I have been back in the hobby about 1 year now. Bought a 26G bowfront tank for my 4 year old daughter to enjoy. We love it some much I just bought a 75 T and will start assembling the pieces to get that up and running. 

In our 26, I have a Corallife 24" and while I have never had a planted tank before, I think thing are going well for the most part with the hartier plants. I am not using C02, just Flourish once per day. I have a 10,000K and a Colormax bulb in this unit.

Now on the 75T, I want to make sure I have the right fixture/bulbs to the plants and fish. 

Based on your amazing research and chart, I was thinking about going with one two bulb 48" (or do I need one 4 bulb fixture?)
http://www.marinedepot.com/AquaticL...xtures-AquaticLife-AK01142-FILTFIT54U-vi.html

and again, no C02. 

Can you please give me your opinion if that set up will work well with the more common plants and fish or do I need more more than one two bulb unit or a different lighting system all together.

Could you also give some feedback on the chart in post #9 of this thread?

http://www.plantedtank.net/forums/showthread.php?t=241970



Thank you in advance for your time and assistance.

Brad


----------



## Hoppy

You should get medium light, around 50-60 micromols of PAR with the two bulb light, but it is unlikely to cover the whole tank with uniform light - the 18 inch front to back width is a lot for one T5 light to cover. You also will have too much light to do without CO2 without having lots of algae problems. You could raise the 2 bulb light to about 10-12 inches above the top of the tank, which should reduce the light down to about 40 micromols of PAR, which might be low enough to avoid big algae problems if you also use Excel. That would also let the single light fixture light up the whole tank pretty uniformly.

The chart you referred to is obsolete now. When it was made I didn't have a lot of data from many different manufacturers T5 lights, and there weren't as many inexpensive ones available. The charts in this thread supersede that old chart.


----------



## hiyabrad

Hoppy said:


> You should get medium light, around 50-60 micromols of PAR with the two bulb light, but it is unlikely to cover the whole tank with uniform light - the 18 inch front to back width is a lot for one T5 light to cover. You also will have too much light to do without CO2 without having lots of algae problems. You could raise the 2 bulb light to about 10-12 inches above the top of the tank, which should reduce the light down to about 40 micromols of PAR, which might be low enough to avoid big algae problems if you also use Excel. That would also let the single light fixture light up the whole tank pretty uniformly.
> 
> The chart you referred to is obsolete now. When it was made I didn't have a lot of data from many different manufacturers T5 lights, and there weren't as many inexpensive ones available. The charts in this thread supersede that old chart.


Thanks Hoppy. To clairfy, the fixture I linked to is a two bulb fixture, not a single T5HO. I will not be able to get it 10-12 inches above the tank so maybe I can use screen to lower the micromols of PAR? Should I buy a 4 bulb fixture so I get more uniform light? I guess I can use C02 but I do not have experience with it. Is there a set up you recommend?

Is there a preferred lighting fixture you would recommend as well?

Thank you, it is greatly apprecaited.


----------



## Hoppy

You could use a pair of FishNeedIt or Coralife 2 bulb T5HO lights, with one near the back and one near the front of the tank. That would give pretty uniform light, and still be low light so you wouldn't need to use CO2. A single light fixture, even with 4 bulbs, will not cover the whole 18 inches of front to back width uniformly unless it is raised several inches above the top of the tank. Adding window screen to reduce the intensity will work, but you would still lack uniform light that way. The reason for using the Coralife or FishNeedIt lights is that they are relatively inefficient, so they don't give you as much intensity as most other lights do.


----------



## madness

I can't believe I missed this earlier.

A masterwork - even compared to your previous lighting threads.

Just wanted to say thanks for putting together a comprehensive post that is, hopefully, neophyte friendly as well.


----------



## chevyguy86

Lighting is so frustrating for me I have bought so many fixtures, and they just did not last long before something happened to it. I currently have a 100g planted discus tank with pressurized Co2. I currently have a 2x48" T5 bulbs but I think the ballast is starting to go on it. Plus I also have a Marineland LED strip with the blue led's which is tarting to shotout at the plug. I want to place both units with 1 single quality unit. I am looking at the ATI 4x54w 48" Dimmable Sunpower. My problem is that I cannot suspend light over the tank. It has to be mounted to the rim of the tank. (wife doesn't want something hanging from the ceiling in our living room) Would this be a good solution, and a last solution for this tank. To much light? What bulbs should I put in it for best light for a planted discus tank. I prefer having a very bright tank during photo period. I would like my show tank back as it is at my front door kinda of a center piece in my house. So frustrated I kinda let it go, but I spent so much on the 7 discus that are in that tank I want to get back into it and get it back to the ohh and ahh factor that I used to have. But I need to start at the lighting.


----------



## PlantedTankRookie

*Finnex Ray 2 info*

Hello all,
I've recently been trying to start up a planted 125 gallon tank. I found much of the info in this forum very useful so I figured I'd share a little about what I have learned about the Finnex Ray 2 daylight fixtures.

The 16" fixture has what I assume is the same LED strip as the 12" fixture. I ordered and returned a 16" fixture because I was not happy with the 10.5" LED strip.
The 24" fixture has about 22.5" of LEDs.
The 48" fixture has two of the strips used on the 24" fixture (45" total width). Both 48" fixtures I received ended up going back because only one side worked.
The 30" fixture has the same LED strip as the 24" fixture.

In general, it appears you can calculate the width of the LED strip by dividing the number of LEDs by 8. Most web sites list the number of LEDs but I haven't seen any list the width of the LED strip. I only know this for the Ray 2 daylight fixtures so I can't speak for the other Finnex LED fixtures.

Hope this helps anybody considering the Ray 2 daylight fixtures.


----------



## Ashnic05

Just to clarify: 

If my tank's dimensions are 36" x 12" x 18" (30 gal) then purchasing an Odyssea T5 HO dual listed here:

http://www.aquatraders.com/36-inch-2x39W-T5-Aquarium-Light-Fixture-p/52122p.htm

Would this give me 50 to 55 PAR? Or medium to high light (more medium)? I want to grow some L. aromatica and Hair grass...would this lighting suffice? Awesome thread Hoppy!


----------



## DaveMcKenz

*Measured my "PAR" 390 watts CFL = 118umols (125g)*

This is a fantastic thread. I have a luxmeter that I put inside a ziplock bag. It is not that easy to handle unless you use a straw to suck out all the air. I put it on the bottom of my 125g tank. It is 18" deep and is running 6 65 watt 6500K CFL lamps (Hamilton). I got an average reading of 9000 lux, which converts by dividing by 76 to 118 umols. I thought my tank was medium to high light, and I guess that is correct. I do have pressurized CO2 and ferts and decent to good plant growth.


----------



## Hoppy

Ashnic05 said:


> Just to clarify:
> 
> If my tank's dimensions are 36" x 12" x 18" (30 gal) then purchasing an Odyssea T5 HO dual listed here:
> 
> http://www.aquatraders.com/36-inch-2x39W-T5-Aquarium-Light-Fixture-p/52122p.htm
> 
> Would this give me 50 to 55 PAR? Or medium to high light (more medium)? I want to grow some L. aromatica and Hair grass...would this lighting suffice? Awesome thread Hoppy!


It would give about that much light, possibly as much as 60 micromols. You need pressurized CO2 to use that much light without constant algae battles, and the plants will grow much better with CO2.


----------



## Steve001

DaveMcKenz said:


> This is a fantastic thread. I have a luxmeter that I put inside a ziplock bag. It is not that easy to handle unless you use a straw to suck out all the air. I put it on the bottom of my 125g tank. It is 18" deep and is running 6 65 watt 6500K CFL lamps (Hamilton). I got an average reading of 9000 lux, which converts by dividing by 76 to 118 umols. I thought my tank was medium to high light, and I guess that is correct. I do have pressurized CO2 and ferts and decent to good plant growth.


To the underlined part. What you don't know is what wavelengths your lux meter is sensitive to so you don't know the PAR numbers expressed as umols and you don't know for certain whether your plants consider this medium to high light or even low light even though your plants seem to do ok.


----------



## assasin6547

Quick question, would a Finnex LED 12" be "high" light for a 7.5 gallon 12x12x12 Mr aqua cube? Is that good enough to grow HC, DHG, Riccia and needle leaf ludwigia?

Thanks


----------



## Ashnic05

Hoppy said:


> It would give about that much light, possibly as much as 60 micromols. You need pressurized CO2 to use that much light without constant algae battles, and the plants will grow much better with CO2.


I fully intend on doing pressurized co2, I've done my homework  My plants will love me for it I'm sure. Now to figure out a good balance! Thanks.


----------



## Hoppy

Steve001 said:


> To the underlined part. What you don't know is what wavelengths your lux meter is sensitive to so you don't know the PAR numbers expressed as umols and you don't know for certain whether your plants consider this medium to high light or even low light even though your plants seem to do ok.


Lux meters measure light in a fairly narrow band centered at about 550 nm wavelength, but they do measure some of the light in the band between about 450 and 650 nm, so they aren't blind to the wavelengths favored by plants.

Almost all of us light our tanks with fluorescent or LED lights, and most of us use predominantly cool white bulbs/LEDs. For that group, which is a large group of us, the conversion factor of 76, or 73, works well enough. Even a Quantum meter can only measure the PAR within 10% or so, and that is also more accurate than we need it to be.

It does no good to pretend that measuring how much light we can get from a specific light fixture is extremely difficult, and beyond the capabilities of most of us. We aren't scientists, and we all know that any light over any tank has zones of widely varying PAR intensities, especially after we put plants and hardscape in the tank. All we need to do is select a light by what the PAR is at the substrate and we will know, within the accuracy we need, that we have a usable light/tank setup.


----------



## Ashnic05

Hoppy said:


> It would give about that much light, possibly as much as 60 micromols. You need pressurized CO2 to use that much light without constant algae battles, and the plants will grow much better with CO2.


Would it be too much light if I were to purchase a quad T5 HO instead of the dual and have 2 x 10,000k daylights, one Actinic and one Magenta? I would be alternating between:

1x10,000k + Actinic & 1x10,000k + Magenta (4 hours each)

Or would it be better to replace one of the 10,000k with a 6,500k? I don't want to run CO2 more than 3bps due to livestock. Again, thanks for the help.


----------



## madness

assasin6547 said:


> Quick question, would a Finnex LED 12" be "high" light for a 7.5 gallon 12x12x12 Mr aqua cube? Is that good enough to grow HC, DHG, Riccia and needle leaf ludwigia?
> 
> Thanks


If I read the charts correctly I think that you will be around 50mmol in a 12" cube tank if you use the Ray 2. Maybe down to 40 or so depending upon the details of the 12" version of the fixture.

That borders on high light. Depending upon who you ask it should grow just about everything. Might be pushing the edge of where you need to run CO2 though.


----------



## hcdcharts

*AH Supply T5HO*

Hello All,

What a great thread. I have a question concerning the AH Supply T5HO Bright Lights they sell with their reflectors. On Hoppy's chart he refers to their PC fixtures and reflectors and PAR readings but no mention of their T5HO lights. I'm sure Hoppy has better things to do than test every fixture on the market....so I have 2 48" T5HO of those lights w/reflectors over a 90 gallon about 24" above the substrate and about 8" apart. I am looking for the high end of medium light. I use CO2, I just do not want to go crazy with it as I use Excel. Is this enough light or not? Are these lights on par with Catalina's line?


----------



## Hoppy

hcdcharts said:


> Hello All,
> 
> What a great thread. I have a question concerning the AH Supply T5HO Bright Lights they sell with their reflectors. On Hoppy's chart he refers to their PC fixtures and reflectors and PAR readings but no mention of their T5HO lights. I'm sure Hoppy has better things to do than test every fixture on the market....so I have 2 48" T5HO of those lights w/reflectors over a 90 gallon about 24" above the substrate and about 8" apart. I am looking for the high end of medium light. I use CO2, I just do not want to go crazy with it as I use Excel. Is this enough light or not? Are these lights on par with Catalina's line?


Someone with access to a PAR meter needs to do some testing to be sure how good those AH Supply T5HO lights are. Based on their reflector design I suspect they are comparable to the Tek or ATI lights, as far as PAR is concerned. So, I suspect each bulb would give you around 25 micromols of PAR at that distance. With the bulbs spaced 8 inches apart you would possibly get almost twice as much PAR with 2 bulbs, possibly a little less. Maybe 40-50 micromols of PAR or medium light.


----------



## hcdcharts

Thanks Hoppy, that helps a great deal!!


----------



## Jeffww

I have a rather long 5g tank with two cfls suspended 15"above the substrate. The lighting is 2x26w in two 8.5" dome reflectors. The bulbs stick out maybe 3/4". Is this too much light? I'm kind of confused because the PAR graph says much over 100PAR which seems like a crazy amount if 50 is already "high light". Even reducing to 13w bulbs doesn't seem to be much different. In fact, I think they might be MORE light since they would be completely contained within the dome. I do have pressurized co2 though...However this is more PAR than what was on my 60p with 2x24w T5HO!

What's your opinion?


----------



## Hoppy

We had difficulties when trying to get repeatable PAR readings with those 8.5 inch diameter reflectors with CFL bulbs. There are just too many variables, including the actual physical size of the bulbs, which varies with manufacturer. I keep thinking I will go back and work on this again, but I haven't done so. I can't figure out a way to get data that will work for a variety of reflectors, bulbs, manufacturers, etc. I hope someone else will work on this.


----------



## Jeffww

Do you think that there's a high likelihood that I have too much light? I'm getting stunting in my R. rotundifolia of all things.


----------



## Hoppy

Jeffww said:


> Do you think that there's a high likelihood that I have too much light? I'm getting stunting in my R. rotundifolia of all things.


Intuitively only, I think you probably have high light, but I don't see that stunting any plants. Any stunting would be from a shortage of a nutrient, probably CO2. With high light you do need a lot of dissolved CO2 in the water to enable the plants to grow as fast as the light is driving them to grow.


----------



## herns

> Any stunting would be from a shortage of a nutrient, probably CO2. With high light you do need a lot of dissolved CO2 in the water to enable the plants to grow as fast as the light is driving them to grow.


Does cutting back lighting period somehow helps stunting growth? Assuming CO2 is up to optimum level but light is just high.

Good info. Thanks for putting this up.


----------



## xmas_one

Just pulled a read with the mrgreen meter, two 70w mh jbj vipers on a 90gal 24*24*36 = 50 par @ 24" deep.


----------



## newbieplanter

I still have no idea what any of this means so be prepaid for questions when I start my new 55+!!!!!!!!!


----------



## latchdan

Can this be made a sticky already


----------



## veryzer

Hoppy, you said somewhere that one can grow pretty much anything with 50-60 par (I think that's accurate...can't find the source material). Does this include red plants? I'm running with about 75 par right now and am thinking of venturing into these more difficult species. Anyone else with first hand experience feel free to chime in.

Thanks


----------



## Hoppy

Growing plants doesn't take more than 40-60 PAR, with good CO2, but many of the plants that looks so good when they have red leaves do need better conditions than just that PAR and CO2. It seems that some need light that encourages the red leaves, and all need light with enough red in it to be able to reflect red so you see the color. That isn't true of all red leaf plants, but it seems to be true of some or even many. I will let some one else describe what it takes for that type of plant to look its best.


----------



## veryzer

"It seems that some need light that encourages the red leaves, and all need light with enough red in it to be able to reflect red so you see the color."

Yeah, I've heard the same. That seems to be the gripe about finnex and other leds. I have led fixtures with 20% 660nm. I guess the only way to find out is give it a try.

Thanks.


----------



## pmcarbrey

I have a question for the resident lighting guru: any par info on the coralife light that has the stock #ENE53008? It uses 2 65W straightpin bulbs.
I am planning on using this for my 12L and have no idea how high I will need to hang it


----------



## Hoppy

Every Coralife light I have seen has had poor reflectors. The Coralife PC fixtures I have seen essentially had no reflector at all. So, those lights can be expected to produce from half to a third of the PAR that a AH Supply PC light produces. But, I don't recall ever seeing any PAR data for those lights.


----------



## PlantedTankRookie

veryzer said:


> "It seems that some need light that encourages the red leaves, and all need light with enough red in it to be able to reflect red so you see the color."
> 
> Yeah, I've heard the same. That seems to be the gripe about finnex and other leds. I have led fixtures with 20% 660nm. I guess the only way to find out is give it a try.
> 
> Thanks.












Are you suggesting that the available red light in the finnex ray 2 daylight LED isn't enough for red plants?


----------



## guacadoggie

Hello. Unless I missed it earlier in this thread, what about compact fluorescent screw-in bulbs? I have two of the following setups on my 48"x24"x18" 75-gal tank. It comes to over 3 watts per gallon, but I'm unsure if the light is dispersing properly.

This: 
http://www.elightbulbs.com/TCP-14680-48932FS-Twist-Medium-Screw-Base-Compact-Fluorescent-Light-Bulb

Plus this:
http://i-cdn.apartmenttherapy.com/uimages/sf/1-14-clamp light.jpg

And here's my tank:
http://sdrv.ms/YaOR0u


----------



## zippymuffin

I am also a newbie and would be really grateful for some lighting related advice.
I have a 80 gallon tank, the dimensions are 48"x20"x20". The distance from the bulbs to the water surface is 4 inches. The tank is fitted with a hood so there is no room to rise the bulbs to a higher level. I bought *5* osram 54w t5HO fluorescent bulbs but after I read this thread (and 2 others) I think I may have gone over the top.
So i guess my question is: If i won't use any reflectors-only white paint- could I use all 5 bulbs without having excessive light?

Ps: I would like to grow carpet plants and some reds


----------



## rhodesengr

So if I am reading the data right, it looks like the Home Depot 23 watt screw in bulbs pretty much blow everything away especially if you figure in the cost. They are well above 100 PAR at 17.5 inches. None of the plotted LED lights do that and only some of the very expensive CFL lights do better.

Is that right?

Hoppy: can you be more specific about the bulb and the the reflector? Links on HD please?


----------



## Hoppy

rhodesengr said:


> So if I am reading the data right, it looks like the Home Depot 23 watt screw in bulbs pretty much blow everything away especially if you figure in the cost. They are well above 100 PAR at 17.5 inches. None of the plotted LED lights do that and only some of the very expensive CFL lights do better.
> 
> Is that right?
> 
> Hoppy: can you be more specific about the bulb and the the reflector? Links on HD please?


http://www.homedepot.com/p/t/100354...reId=10051&N=5yc1v&R=100354511#specifications is the reflector, and the bulbs are just 6500K screw-in CFL bulbs. You do need to have them about every 12 inches over the length of the tank, to get reasonably uniform light.


----------



## rhodesengr

Hoppy said:


> http://www.homedepot.com/p/t/100354...reId=10051&N=5yc1v&R=100354511#specifications is the reflector, and the bulbs are just 6500K screw-in CFL bulbs. You do need to have them about every 12 inches over the length of the tank, to get reasonably uniform light.


so are the measurements from the bottom of the reflector or where the bulb is located. The reflector move the bulb up a ways.

I do get you need to space them across the tank but this seems like a really cheap way to to get a big increase over a single AH supply 55 watt. Is that right or am I misreading the data?

Does not seem like you can get anywhere near the same light with LED's.


----------



## TigerBarb75

*31 " Tall tank*

Good day,

All this is german to me :smile: I currently have 2 x 8000k t5 54w with Juwel Aquarium reflectors. And 1 x 6500k t5 54w My tank dimensions are 
66 long x 21 w x 31 h I am not using pressurized c02 is this lighting sufficient for my plants to grow decent. I am getting good growth though just want to know if I need more light. Maybe another 8000k t5 54w or anothet 6500k t5 54w.

This is a medium planted freshwater tank.

Is the Par rating fine with these tubes.

This tank is about 180 gallons.

Please advise.

Thanks a mil.


----------



## Rigio

Gafi said:


> what are you thoughts on this lighting fixture Hoppy http://www.jlaquatics.com/product/s...Light+4+Bulb+T5+Fixture+(48+Inch,+4x54W).html
> 
> PS the issue with the Catalina ones, are I am not sure they ship to Canada and if they do, im sure it would be ridiculous



I just read your comments, and I was wondering I'd you've contacted catalina to inquire about shipping as I've been interested in their products for awhile but haven't followed up as I don't have the money yet


----------



## Hoppy

rhodesengr said:


> so are the measurements from the bottom of the reflector or where the bulb is located. The reflector move the bulb up a ways.
> 
> I do get you need to space them across the tank but this seems like a really cheap way to to get a big increase over a single AH supply 55 watt. Is that right or am I misreading the data?
> 
> Does not seem like you can get anywhere near the same light with LED's.


In general, measure from the bulb, but these charts are only approximate, so unless the bulb is 2+ inches from the reflector edge it won't make much difference whether you use the edge of the reflector or the bulb.



TigerBarb75 said:


> Good day,
> 
> All this is german to me :smile: I currently have 2 x 8000k t5 54w with Juwel Aquarium reflectors. And 1 x 6500k t5 54w My tank dimensions are
> 66 long x 21 w x 31 h I am not using pressurized c02 is this lighting sufficient for my plants to grow decent. I am getting good growth though just want to know if I need more light. Maybe another 8000k t5 54w or anothet 6500k t5 54w.
> 
> This is a medium planted freshwater tank.
> 
> Is the Par rating fine with these tubes.
> 
> This tank is about 180 gallons.
> 
> Please advise.
> 
> Thanks a mil.


The color temperature of the bulb doesn't have much effect on the PAR you get from each bulb. It affects how the tank looks, so that is a personal choice. How much light intensity you get depends on how the bulbs are arranged above the tank. They are about 20 inches shorter than the tank length, to start with, and the tank has too great a front to back depth for one row of bulbs to light it uniformly front to back, so you would want 2 rows of bulbs, but that would leave the ends darker than the center. How are the bulbs arranged?


----------



## zippymuffin

zippymuffin said:


> I am also a newbie and would be really grateful for some lighting related advice.
> I have a 80 gallon tank, the dimensions are 48"x20"x20". The distance from the bulbs to the water surface is 4 inches. The tank is fitted with a hood so there is no room to rise the bulbs to a higher level. I bought 5 osram 54w t5HO fluorescent bulbs but after I read this thread (and 2 others) I think I may have gone over the top.
> So i guess my question is: If i won't use any reflectors-only white paint- could I use all 5 bulbs without having excessive light?
> 
> Ps: I would like to grow carpet plants and some reds


Because i got no advice, I left the hood bare for now, with no reflectors at all. It's a new setup, so I only light 2 bulbs at a time and I will gradually increase the amount of light by turning on more bulbs. The light diffuses evenly across the tank even without reflectors...but will this be enough? 
I can't calculate the amount of PAR because -if I understood correctly-the charts only show the light fixtures with the reflectors already installed.


----------



## veryzer

Sorry for the long delay, but that's what many people have complained about. LEDs with 660ns (red) lights tend to have a higher red hump.



PlantedTankRookie said:


> Are you suggesting that the available red light in the finnex ray 2 daylight LED isn't enough for red plants?


----------



## KrystyonWayne24

ok I am new here and trying to be cheap and also trying to understand the lighting stuff.
I have 75gal 48"X18X20 that I am wanting to grow medium/low light plants. I am not sure I understand this right but I am planning on using CFL bulbs and 10.5 or 8.5 clamp lights. For me to get around 40-45par I think is what I need I would need 2 10.5 with say 13/60w CFLs in them or would that be enought or should go with the 8.5's and go with 4 and the 13w CFLs? Please help


----------



## Hoppy

KrystyonWayne24 said:


> ok I am new here and trying to be cheap and also trying to understand the lighting stuff.
> I have 75gal 48"X18X20 that I am wanting to grow medium/low light plants. I am not sure I understand this right but I am planning on using CFL bulbs and 10.5 or 8.5 clamp lights. For me to get around 40-45par I think is what I need I would need 2 10.5 with say 13/60w CFLs in them or would that be enought or should go with the 8.5's and go with 4 and the 13w CFLs? Please help


It will be hard to get uniform light on a 75 gallon tank, using those dome reflectors. They tend to light up an area just a bit bigger than the dome diameter. If you use the 10.5 inch diameter dome reflectors you would need 4 of them across the length of the tank to stand a chance of getting uniform lighting. They need to be at least an inch above the top of the tank to allow for air circulation to cool the bulbs, so the lights would be about 21 inches from the substrate if you use 2 inches of substrate. At that distance I suspect you will need at least 20 watt and probably 25 watt CFL bulbs, not 13 watt, which are good for 10 gallon tanks. It might be cheaper to use a Odyssea 2 bulb T5HO light, suspended about 6 inches above the top of the tank.


----------



## steveo

Hoppy- Great article!

Marineland provides extensive PAR data for their Aquatic Plant Lights. For example, as printed on the box, their 24" version provides up to 172 PAR at a 12" depth and 83 PAR at a 24" depth. Is this one of the higher PAR producing LED strip lights on the market?


----------



## TB3Redneck

Because I can't seem to follow all the technical talk, maybe the boss can do it for me lol. So I've got a 29 gallon and the 17 watt T8 24" Aqueon bulb sits 17" from the surface. What would the par rating be around for this? 

Sent from my SGH-T999 using Xparent Skyblue Tapatalk 2


----------



## Hoppy

TB3Redneck said:


> Because I can't seem to follow all the technical talk, maybe the boss can do it for me lol. So I've got a 29 gallon and the 17 watt T8 24" Aqueon bulb sits 17" from the surface. What would the par rating be around for this?
> 
> Sent from my SGH-T999 using Xparent Skyblue Tapatalk 2


Probably around 30 PAR units, or good low light.


----------



## FlyingHellFish

Hey Hoppy, got questions for you. 

1.If a light source has enough PAR but very little red/blue spectrum, can you still achieve deep red/purple colouring of plants? 

2.I'm not sure which spectrum is needed to get those colours so substitute x value. Basically, if you have enough PAR will you get the colours regardless of spectrum? 

3.Could one use a full spectrum bulb to cover all the requirements or does it have to be HIGH RED to achieve x colour , HIGH BLUE to achieve x colour. 

Thanks.


----------



## Hoppy

FlyingHellFish said:


> Hey Hoppy, got questions for you.
> 
> 1.If a light source has enough PAR but very little red/blue spectrum, can you still achieve deep red/purple colouring of plants?
> 
> 2.I'm not sure which spectrum is needed to get those colours so substitute x value. Basically, if you have enough PAR will you get the colours regardless of spectrum?
> 
> 3.Could one use a full spectrum bulb to cover all the requirements or does it have to be HIGH RED to achieve x colour , HIGH BLUE to achieve x colour.
> 
> Thanks.


I don't know the answer. I'm not even sure that anyone has done the necessary testing to answer the question. From what I read it seems that getting good red colors in plants is a lot easier if you use higher light intensity than is absolutely necessary to grow the plants. But, whether that can be done by just adding more red and/or blue to the spectrum seems not to have been determined yet.


----------



## TB3Redneck

Hoppy said:


> Probably around 30 PAR units, or good low light.


Ok that sounds alright. My tank is also heavy with tannin, so I believe that would also lower the par reaching the substrate? I'm thinking of converting my fixture into a two bulb screw in CFL fixture? What would that put the par around? 
Thanks again! 

Sent from my SGH-T999 using Xparent Skyblue Tapatalk 2


----------



## Falconeyes88

Hi Hoppy.
Heard you were the guy to ask about Lights. I just bought a 24inch Fluval "plant LED" light for my 10 gallon. without the brackets there is almost no overhang. but I was worried about PAR. do you know if this light is ok for a 10 gallon? I am very new and don't even have water or substrate in the tank yet cause I wanted to get everything right the first time.

Feel free to PM me. Thank you in advance! 

reason I ask if its an ok light is because it was $159 and if there is something better for that price or lower I would love to know what it is.


----------



## theericafish

This thread helped me a lot in deciding which light to get for my 20l. Just saying thanks!


----------



## dstevenson2k

Hey Hoppy or anyone else,

How would the Zoomed Aquasun rate among the T5HO units? I know they don't have the best reflectors, not sure about their ballasts. Any PAR data out there for these units?


----------



## Aquaticz

Rigio said:


> I just read your comments, and I was wondering I'd you've contacted catalina to inquire about shipping as I've been interested in their products for awhile but haven't followed up as I don't have the money yet


I have four of their fixtures. I really suggest you call. I find his fixtures very competitive in price, its a good product. Make sure you get splash guard


----------



## KrystyonWayne24

Hey Hoppy would a SB and a DB from Marineland be enought to light my tank for low light plants? I have chance to trade for a 36"-48" single and double bright and was wondering if they would produce enough par for my tank as it is 75gal and they will be about 21" from substrate.


----------



## Hoppy

The double bright light will give good low light on that tank, but may not cover the whole tank, because of its 18 inch front to back depth. The single bright will add very little more light.


----------



## KrystyonWayne24

I found this on ebay will it be better than the marineland DB leds or not. I'm trying to figure out cause got a guy wanting to trade for guitar on Marinelands and have money for fixture on [Ebay Link Removed]

48" - 52" Freshwater Bright LED by Beamworks
Dimensions - 47.75” x 5.00” x 1.00”
Brackets add 0.65" in height
Includes 174 LEDs
900 Lumen
Super energy efficient .06 watt LEDs
162x 10000K LEDs
12x Actinic 460nm LEDs
Uses 11 watts
Slim and contemporary light design
2 mode on / off function for day and night use
Extendable bracket - 48"-52" max extend
Splash guard
110V - 220V


----------



## owens81jw

KrystyonWayne24 said:


> I found this on ebay will it be better than the marineland DB leds or not. I'm trying to figure out cause got a guy wanting to trade for guitar on Marinelands and have money for fixture on [Ebay Link Removed]
> 
> 48" - 52" Freshwater Bright LED by Beamworks
> Dimensions - 47.75” x 5.00” x 1.00”
> Brackets add 0.65" in height
> Includes 174 LEDs
> 900 Lumen
> Super energy efficient .06 watt LEDs
> 162x 10000K LEDs
> 12x Actinic 460nm LEDs
> Uses 11 watts
> Slim and contemporary light design
> 2 mode on / off function for day and night use
> Extendable bracket - 48"-52" max extend
> Splash guard
> 110V - 220V



those 12x Actinic 460nm LEDs are useless to plants i think


----------



## jkpedrita

What a great job Hoppy! I joined the forum just to say thank you. I was so inspired reading through the posts that I ran out to get two brooder lamps and 13 watt 6500k CFLs for my 20H. The difference between the stock t-8 light and the cfls is visible to the naked eye. Thanks!


----------



## jeffkrol

owens81jw said:


> those 12x Actinic 460nm LEDs are useless to plants i think


If you check out the PAR spectrum it becomes clearer:








(Green is roughly 500-550nm)
PAR or PUR is a bit redundant in so much of the fact that a "perfect" PAR would be close to a perfect PUR light system AFAIKT. Some corals and other organ. I believe also contain Chlorophyll "c" which is neither here nor there for "our" purposes. There are a few other forms of chlorophyll as well. The kicker is Carotenoids also participate and as shown above, have their own absorption band.. 


> Carotenoids are usually considered to perform two major functions in photosynthesis. They serve as accessory light harvesting pigments, extending the range of wavelengths over which light can drive photosynthesis, and they act to protect the chlorophyll pigments from the harmful photodestructive reaction which occurs in the presence of oxygen.


Then you have aesthetics.. any look at pure "grow lights" esp in the LED form will show you lights that are not "pleasing" (just got done building one of them, but will admit it can grow on you) 
LED's have very specific "spot patterns" and some colors are enhanced or spread out using filters or the same phosphors you get in other lights. Fluorescent tubes have same spiky nature and are also enhanced w/ phosphors to get around it. HID ect (heat bulbs w/ light properties )have a more spread spectrum but are naturally abundant in the ones least needed, IR and UV creating large energy consumption and loss (through heat and UV shielding) for less bang for the buck so to speak. No harm intended, the PAR is in some regards better than other lights (fewer holes) just a comment on the cost of that spectrum.

Of course plants have other hormone responses to light as well but then it gets really messy.
(MORE than we care to know example )


> In this review we discuss the interactions between light and plant hormones and their role in mediating phenotypic change during de-etiolation. Clear evidence exists for a light-mediated reduction in gibberellin A, GA levels and response in pea, which is thought to be responsible, at least in part, for the reduction of shoot elongation during de-etiolation.


sorry just my 2 cents.
someone elses 2 cents:


> Recommendations for optimal LED designs vary widely. According to one source, to maximize plant growth and health using available and affordable LEDs, U.S. patent #6921182 from July 2005 claims that "the proportion of twelve red 660 nm LEDs, plus six orange 612 nm LEDs and one blue 470 nm LED was optimal", such that the ratio of blue light to red & orange light is 6-8%.[1]


Pumpkin orange tank and washed out looking really healthy plants anyone???


> It is also often published that for vegetative growth, blue LEDs are preferred, where the light has a wavelength somewhere in the mid-400 nm (nanometers). For growing fruits or flowers, a greater proportion of deep-red LEDs is considered preferable, with light very near 660 nm, the exact number this wavelength being much more critical than for the blue LED. Further research has shown that infrared and ultraviolet diodes give a full spectrum needed for flowering plants to effectively grow and flower.[1][_citation needed_]


Fun stuff... 
Of course this is not a water environment and doesn't have the same problems as mentioned earlier (spectrum dilution due to depth, diffraction due to water)
The beauty of LED's is watts are no longer a driving factor as compared to the "old days" when you had to push massive watts to provide peak spectrums in the important bands..
From a very brief dabble in this 50w of targeted LED's seems to be more efficient than 100w HO or gosh knows how many of HID type bulbs... 

As to component/consumable costs.. night and day.. 

all arguable of course..


----------



## Maxspin

What a great thread. Thanks for doing this.

I just replaced the shop light fixture on our 75 gal with the (HD diamond plate shop light). Just looked at the PAR chart for that light!!! Oops this is supposed to be a low light low tech tank. 

Did I just screw up?

Keith


----------



## FlyingHellFish

Great write up Jeff, very interesting opinions. 

I would love to get some PAR reading from a narrow reflector for common CFL, I suspect they produce a lot more PAR. Looking at Hoppy's chart (thanks for the effort btw), I'm surprise at the number like everyone else. 

Wouldn't these Shop set up be the most cost effective solution? I know they have full UVB or "grow lights" so one can mix their lighting. 

Here my experience, take it for what it's worth. - 

I picked up some "full spectrum" CFL made with a wider range rather than peaks, it was the same spec as a common CFL. I replace my lighting with these "full spectrum" 23w 6500K and notice for the first time, algae. I switched back to my old 23w 6500k and I kid you not, the algae went away. I'm confused, algae usually doesn't start and go that fast. 1 week algae starts, next week algae dies off. :S

Also, if one were to focus mainly on colour intensity of the plants rather than the growth, would it not be ideal to have both lights peaking in blue and red? To compensate for brightness you can just get a plain 6500k bulb to accompany them. I'm talking about purple/red hues on plants, making plants green is passé.


----------



## Water7

This is an amazing thread. I am sitting here trying to digest that what I thought was a medium-low light tank is actually a high light tank. Please correct me if I'm wrong. I have a typical 20 gallon long tank with non-demanding plants. I have DIY CO2 which is not as prolific as I'd like. The last time I counted it was doing 16 bubbles per minute but it changes.

I have a simple shop light fixture with no reflector holding 2 T8 bulbs (longer than the tank). I figured it out to be around 2 watts per gallon, which I understood to be the upper limit of "low light." But according to the chart, given that my substrate is about 9 and 3/4 inches from my substrate, I have more than 88 PAR. Is this true?

My tank is topped with an old, flat piece of auto glass. (I know that may sound funny, but it was free.) I do not know whether the thickness, or some buildup on the glass has a large effect on the light, but even if it reduced it by 20%, it looks like I'd still be in the high light category.

My anubias pearls wonderfully. I did not know an anubias would do that. It is getting new leaves and has only been in the tank a little more than 2 weeks. The java fern pearls wonderfully too. I do not yet have my ferts going properly, as I'm awaiting their arrival in the mail. However, knowing my true lighting intensity is important to knowing how many weekly EI doses I ought to use. I was planning on just one.

Also I've had a number of different kinds of algae. None of it has become really out of hand, although it's still more than I would like. But it has mostly stayed manageable.

Thank you for any advice. I am still new at this!


----------



## jeffkrol

Water7 said:


> This is an amazing thread. I am sitting here trying to digest that what I thought was a medium-low light tank is actually a high light tank. Please correct me if I'm wrong. I have a typical 20 gallon long tank with non-demanding plants. I have DIY CO2 which is not as prolific as I'd like. The last time I counted it was doing 16 bubbles per minute but it changes.
> 
> I have a simple shop light fixture with no reflector holding 2 T8 bulbs (longer than the tank). I figured it out to be around 2 watts per gallon, which I understood to be the upper limit of "low light." But according to the chart, given that my substrate is about 9 and 3/4 inches from my substrate, I have more than 88 PAR. Is this true?
> 
> My tank is topped with an old, flat piece of auto glass. (I know that may sound funny, but it was free.) I do not know whether the thickness, or some buildup on the glass has a large effect on the light, but even if it reduced it by 20%, it looks like I'd still be in the high light category.
> 
> My anubias pearls wonderfully. I did not know an anubias would do that. It is getting new leaves and has only been in the tank a little more than 2 weeks. The java fern pearls wonderfully too. I do not yet have my ferts going properly, as I'm awaiting their arrival in the mail. However, knowing my true lighting intensity is important to knowing how many weekly EI doses I ought to use. I was planning on just one.
> 
> Also I've had a number of different kinds of algae. None of it has become really out of hand, although it's still more than I would like. But it has mostly stayed manageable.
> 
> Thank you for any advice. I am still new at this!


proof of the pudding is in the eating...


Unless you have old auto glass it most likely has some sort of optical coating to cut out certain detrimental wavelengths.. mostly UV 


> After the glass is tempered and cleaned, it goes through a laminating process. In this process, two sheets of glass are bonded together with a layer of plastic (the plastic layer goes inside the two glass sheets). The lamination takes place in an autoclave, a special oven that uses both heat and pressure to form a single, strong unit that is resistant to tearing. The plastic interlayer is often tinted to act as an ultraviolet filter.
> Read more: http://www.answers.com/topic/automobile-windshield#ixzz2Vm6OCabL
> ​


not that it seems to matter much.
As to light "falloff" it is logrythmic.. 
Everything one didn't want to know about light in lakes (large aquariums  )
http://www.esf.edu/efb/schulz/Limnology/Light.html


----------



## DaveFish

I don't see ah supply T5HO this time around! I have 3x 54 watt T5HO from ahsupply and I bet it blows the other multi bulb fixtures out of the water!


----------



## DaveFish

FlyingHellFish said:


> Great write up Jeff, very interesting opinions.
> 
> I would love to get some PAR reading from a narrow reflector for common CFL, I suspect they produce a lot more PAR. Looking at Hoppy's chart (thanks for the effort btw), I'm surprise at the number like everyone else.
> 
> Wouldn't these Shop set up be the most cost effective solution? I know they have full UVB or "grow lights" so one can mix their lighting.
> 
> Here my experience, take it for what it's worth. -
> 
> I picked up some "full spectrum" CFL made with a wider range rather than peaks, it was the same spec as a common CFL. I replace my lighting with these "full spectrum" 23w 6500K and notice for the first time, algae. I switched back to my old 23w 6500k and I kid you not, the algae went away. I'm confused, algae usually doesn't start and go that fast. 1 week algae starts, next week algae dies off. :S
> 
> Also, if one were to focus mainly on colour intensity of the plants rather than the growth, would it not be ideal to have both lights peaking in blue and red? To compensate for brightness you can just get a plain 6500k bulb to accompany them. I'm talking about purple/red hues on plants, making plants green is passé.


 Most cost-effective is LED lights. My Finnex are going to last between 8-13 years before I have to replace. Actually peaking red and blue creates more color.


----------



## DaveFish

jeffkrol said:


> If you check out the PAR spectrum it becomes clearer:
> 
> 
> 
> 
> 
> 
> 
> 
> (Green is roughly 500-550nm)
> PAR or PUR is a bit redundant in so much of the fact that a "perfect" PAR would be close to a perfect PUR light system AFAIKT. Some corals and other organ. I believe also contain Chlorophyll "c" which is neither here nor there for "our" purposes. There are a few other forms of chlorophyll as well. The kicker is Carotenoids also participate and as shown above, have their own absorption band..
> Then you have aesthetics.. any look at pure "grow lights" esp in the LED form will show you lights that are not "pleasing" (just got done building one of them, but will admit it can grow on you)
> LED's have very specific "spot patterns" and some colors are enhanced or spread out using filters or the same phosphors you get in other lights. Fluorescent tubes have same spiky nature and are also enhanced w/ phosphors to get around it. HID ect (heat bulbs w/ light properties )have a more spread spectrum but are naturally abundant in the ones least needed, IR and UV creating large energy consumption and loss (through heat and UV shielding) for less bang for the buck so to speak. No harm intended, the PAR is in some regards better than other lights (fewer holes) just a comment on the cost of that spectrum.
> 
> Of course plants have other hormone responses to light as well but then it gets really messy.
> (MORE than we care to know example )
> sorry just my 2 cents.
> someone elses 2 cents:
> 
> Pumpkin orange tank and washed out looking really healthy plants anyone???
> Fun stuff...
> Of course this is not a water environment and doesn't have the same problems as mentioned earlier (spectrum dilution due to depth, diffraction due to water)
> The beauty of LED's is watts are no longer a driving factor as compared to the "old days" when you had to push massive watts to provide peak spectrums in the important bands..
> From a very brief dabble in this 50w of targeted LED's seems to be more efficient than 100w HO or gosh knows how many of HID type bulbs...
> 
> As to component/consumable costs.. night and day..
> 
> all arguable of course..


 Great comment! Simple, Powerful LEDs with high blue and red output. That is all that matters, that is all we need to know. lol


----------



## Water7

Thank you Jeffkrol for your reply to my question. It's possible that my glass may have something like that, as I don't know how old it is. I hope that using it will not be a problem. I have little children and I'm afraid they will climb up and reach into the tank, so the glass prevents that. That's why I'm using it.


----------



## mostman

What would we do without Hoppy? 

Here is a question I have. Over my 55 I have a Catalina 2x54 t5ho. My bulbs, however, are not 7.5 inches apart. I think I just bought the standard fixture - and my bulbs are about an inch apart. Has anyone measured this fixture? Wondering if I need a different fixture to get "high light".


----------



## jeffkrol

DaveFish said:


> Great comment! Simple, Powerful LEDs with high blue and red output. That is all that matters, that is all we need to know. lol


Since I have been tinkering in this area I thought I'd show you some real world shots.
I used 3 drivers
1)powers 3-10w LED pucks w/ 6 "royal blue" and 3 10k "white" per puck, in series
2) 2- 10 W 660nm red LED pucks 9 led's per puck in series
3)15- 1 W single chip "warm white" (which were not nearly matched in color temp) spread out. (3 parallel strands of 5 each, in line interwoven
All have 110-ish degree lenses since being a shallow tank there was no need to beam anything down. Needless to say the puck only light was very disco-ey depending on how dim or bright the red LED's were set at. 
The 1W warm whites smoothed everything out to the eye. Camera is more sensitive to minor differences .










SECOND photo is a bout 65w total (probably less due to underdriving the "blue/white","red", and "warm white" LED's.
Power supplies are 2 Meanwells running off line current (1 dimmable) and a 24v DC printer ps feeding some cheap chinese "recharger" board w/ v and A adj. I'm going to eventually upgrade/change some of the drivers so 1)more dimming options and 2) not such a rats nest.




































"just blue/10K"...


----------



## jeffkrol

One followup: Added a dimmer/driver to the blue channel. Epoxied WW Led light bar to main 10w heat sinks... Have some odd optical reflections to deal with (like why the red LED lights the front bottom more than any other light source..

Anyways an interesting "blend"...









Additional comments: You can see the Olive Nerites (Can't begin to tell you how much I LOVE them for "maintenance") and a "ammonia patch".. cute little spot check device since I was tired of trying to figure out what my API ammonia test results really were... never was "yellow" so I had to "calibrate' using bottled water to compare.. Now I just look.. .. Next I have to see if I can get more "polish" on my water.. On to get some felt for a "micron filter"..

Oh and I realize it is "messy"...


----------



## jeffkrol

Addendum.. found reason behind color banding (I out-tricked myself) . The 1w "warm whites" were thermal epoxied on an l shaped piece of aluminum. Orig thought was to shield the 10w pucks from your vision. I had hoped the "native" 110 degree angle would compensate for the shading effect. It didn't. It can be somewaht compensated by tilting but that is an issue in itself.. 

It does give me some interesting effects though.. 
anyways I'm adding my sunset color and an image of the light construction:

Oh and the 20gal "holding tank" lit w/ a Marineland "puck"

FYI the lights run at about 110F with passive cooling......


----------



## hiyabrad

Hi Hoppy, 

I just bought a new 100g tank. The dimensions are: 60" long, 18" wide, 21" high. 

I will be growing plants but do not want to have C02. I will use Seachem Flourish. I assume I will want a 60" fixture? Can you recommend a lighting set up? And should I be using more additives than just Seachem Flourish?

Thank you in advance. Brad


----------



## rwong2k

noob question, reading those charts from page 1, for 23 watt cfl vs. finnex ray2 for par readings, 18" below surface,


the 23 watt and finnex ray2 has about the same par values or am I reading this incorrectly?


----------



## majorwoo

Someone needs to sticky this thread again.

And thanks Hoppy for all your work, I find myself constantly referencing this thread in my own work and sending other people here.


----------



## Hoppy

majorwoo said:


> Someone needs to sticky this thread again.
> 
> And thanks Hoppy for all your work, I find myself constantly referencing this thread in my own work and sending other people here.


TPT doesn't use "stickies" now. Instead we use a FAQ section, as the first post in each forum. This is one of the FAQ threads listed there at: http://www.plantedtank.net/forums/showthread.php?t=184634


----------



## nickao

*cfl bulbs*

Hoppy,
Do you remember the brand for the HD cfl bulbs you did the par test on? If I have a glass top on my tank does that change the par value? Thanks for this great write up.


----------



## Hoppy

nickao said:


> Hoppy,
> Do you remember the brand for the HD cfl bulbs you did the par test on? If I have a glass top on my tank does that change the par value? Thanks for this great write up.


No, I don't remember the brand of those bulbs. While we were doing PAR tests on CFL bulbs, we noticed that our data were not consistent. A lot depended on how long the bulb was - how much of it stuck out of the reflector. And, it depended on the diameter of that reflector. Since then I haven't gone back to that subject to try to get more usable data. It would help if someone did that - *very carefully*.

The top glass on a tank seems to reduce the PAR by around 10-15%, not very significant, considering that our PAR data is rarely better than +/- 10% accurate.


----------



## plantedtank3141

I can't seem to find any information in this thread regarding the Aqueon LED systems. Did I miss it, or does anyone know what kind of output they have? 

I currently have 3 20" led strips with 9 LEDs each from Aqueon on my 20 gallon tank. Two are white and one is their "colormax" with alternating white and red LEDs. I have no clue how broad their spectra are or how much of the light they put out is actually useful for my plants. Does anyone know?


----------



## Sgtreef

Great read , are you going to do VHO bulbs?

Oops T12 's are VHO.


Jeff


----------



## JerSaint

Hi Hoppy,
Awesome work here! I picked up a 30" ZooMed AquaSun T5HO fixture with dual 24" bulbs. I am using these grow bulbs I found on the cheap http://www.thelashop.com/4x-24w-3000k-2ft-t5-ho-grow-light-fluorescent-tubes.html .

I think it may be overkill directly over my 20 Long but wanted to see if you had any info on the PAR values this fixture puts out at different heights. Any help is appreciated, Thanks!


----------



## gus6464

I have PAR data for the Home Depot PAR38 5000K 18w bulbs if anyone is interested. Ecosmart brand.


----------



## MMantelli

Sweet let's see it!


----------



## vvDO

mmantelli said:


> sweet let's see it!


+1.


----------



## Borsig

I am doing a 180g. My first planted tank.

I would like the "shimmer" of LED's but dont have alot of money to spend on lights. 

Does anyone know the PAR ratings of the beamsworks LED fixtures? I could place one of those in 72", then do a HD shop light for the bright part of the day? 

If I just did the HD shop light how many would I need over a 6 ft tank? I cant go higher than like 6" off the surface though. 

I could also build an LED light, or try to, but my budget is like $250.


----------



## gus6464

Ecosmart PAR38 18W 5000K










I would say 30" from sub would be the sweet spot for a medium-high light cube. I got this bulb for $10 at HD. Perfect cheap bulb for those 7.5g cubes.


----------



## MMantelli

Nice is there any way to get par data for a G.E. 26w 6400k 1610 lumen daylight CFL bulb over say a basic 10g.


----------



## richlids

I'm considering getting two of the 



lights for a 12 gallon long aquarium. Do you guys think that I would need to use CO2 to keep down algae levels with this setup or would I be okay just using shrimp to keep algae under control?


----------



## bigred87

Waaaait!! so Hoppy if i place a Home Depot 2 bulb Diamond Plate Shop Light on top of my 60 gallon ( 24in from the gravel) I am going to have Medium light???


----------



## Nightspell

NicholeFollowell said:


> then why all are spendint the time wasting on the rubbish comments?


Care to elaborate? I believe the rubbish comments are the product of an active discussion...


----------



## khuancc

Hi All, need some quick help, planning to put 6 tubes of t5ho 80watts over 36 inches abaove substrates (tank height is 30 inches and the lowest i can go is 36 inches). Consider high lights? i need high lights please. Thanks in advance.


----------



## Hoppy

You should get around 60-70 PAR with a 4 bulb AquaticLife T5HO light. A 6 bulb AquaticLife fixture should give about 50% more light. Either one would qualify as high light, as I see it.


----------



## OVT

gus6464 said:


> Ecosmart PAR38 18W 5000K
> 
> 
> 
> 
> 
> 
> 
> 
> 
> 
> I would say 30" from sub would be the sweet spot for a medium-high light cube. I got this bulb for $10 at HD. Perfect cheap bulb for those 7.5g cubes.


Gus, missed this one.
Very useful info - ty!
Looks like a spotlight, pretty interesting narrow beam close up. Now, waiting for sale 

v3


----------



## AquaAurora

I notice there's a note about screen covers reducing PAR by 30%, what about if a plexiglass cover is between the light and the water (with light raised a bit above the cover and water)? How will this effect the PAR (if at all)?


----------



## khuancc

Hoppy said:


> You should get around 60-70 PAR with a 4 bulb AquaticLife T5HO light. A 6 bulb AquaticLife fixture should give about 50% more light. Either one would qualify as high light, as I see it.


Thanks hoppy. I got the 6 tubes in the end. Hehe.


----------



## koala

I have a 36" 40g bowfront I'd like to turn into a planted tank... Any decent t5 lighting fixtures that could get me into the low or medium light range that are under 150$?


----------



## saiko

Hi everyone,
Has anyone done a PAR reading on ADA Aquasky? If so please can you direct me to that post.

Thanks in advance.


----------



## vvDO

http://www.plantedtank.net/forums/showthread.php?t=298722



saiko said:


> Hi everyone,
> Has anyone done a PAR reading on ADA Aquasky? If so please can you direct me to that post.
> 
> Thanks in advance.


----------



## saiko

vvDO said:


> http://www.plantedtank.net/forums/showthread.php?t=298722


Thank you vvDOroud:


----------



## Arkansas

Hoppy – This whole tread is outstanding and really answers so many questions about lighting. I’m an older guy just getting back into the hobby and this talk of lighting is quite confusing. 
I have graduated from the old T-12s and am now using T-8s, although T-5s and LEDs are probably the way to go – I’m sticking with the 32 watts T-8s (6500K) for right now. So here is my question for you. I have a 55 gal tank: 48”long x 12”wide x 18” from the bottom of the T-8 tube to the top of the substrate. It is a dirted tank, with the usual low to medium light plants. I just started using 2 shop type lights, each with 2 bulbs for a total of 4) T-8 bulbs. The box for one of the shop sets says: for 2 bulbs = 3100(x2) Lumens, Lumens per watt – 96.8, CRI 86, Ballast Factor Multiplier 0.93
The question is 4 bulbs too many? Are 2 bulbs not enough? All bulbs are 6500K Daylight. I don’t appear to be having excessive or any algae, my dwarf sag is finally growing and my jungle val is going nuts. Thanks for your time. - Chris


----------



## tyronegenade

Hello,

I'm jumping in here a bit late, but reading the thread and the questions and difficulties that people are having are the product of a serious misunderstanding best encapsulated in the following statement:



Hoppy said:


> PAR isn't something that you put into the tank. It is the intensity of the light at various points in the tank.


PAR is something you can put into your tank. It is measured in microEinsteins which is a measure of the number of photons (these are real things!). What is being measured with PAR-meters, and what Hoppy is talking about is Photosynthetic Photon Flux (PPF), also called Phososynthetic Photon Flux Density (PPFD). This is measured in microEinsteins per square meter per second. So, to summate,
PAR = uE
PPF = uE/m2/s

From the data accumulated at http://www.apsa.co.za/board/index.php?topic=4454.0 (in 2010) it is calculated that, on average, you get about 1 PAR/W from tube/fluorescent lamps (T8 & T5). (T5s are only marginally better for output and this is due, mostly, to geometry.) So a 20 W CFL will put out as much PAR as a 20 W T8 tube (because the physics of light emission process is the same). Of course the CFL is all twisted and a lot of light is lost among the twists and turns of the tube (especially as about 30-40% of the light emitting surface is facing another light emitting surface and gets lost by "squishing"). PAR output of LEDs varies from 1.55 to 1.03 PAR/W (depending on bias current) but the geometry of the lamps greatly increases efficiency as the light in concentrated over a narrow beam focus. We suspect that LEDs are, in the end, 3 times more efficient than tube lamps based on the number of LED watts needed to get plants to pearl compared to T5 tubes.

Using this data, and Tom Barr's PPF data for actual planted aquariums and scientific journals for attenuation coefficients* we worked out the following: http://www.apsa.co.za/board/index.php?topic=4454.msg109062#msg109062 (and have been fine tuning it since 2010 as we gathered more data). This is our best guess for how many watts you need over a tank to achieve 40 PPF at a certain depth.

The major factors (that will vary with each aquarium setup) are the turbidity of the water (the more light absorbing dissolved solids the more light is absorbed with depth), the amount of light lost to reflection due to surface disturbance or angle of lamp to water (90% of the light hitting the water at 60o is reflected and it gets worse the shallower the angle). You need the lamps as close to the water as possible to keep the angle of incidence steep. The quality of your reflector is also critical. With a bad reflector you are probably getting less than 50% of your light into the tank. With no reflector the value is closer to 30%. A model to determine reflector efficiency is available at http://www.apsa.co.za/board/index.php?topic=4379.msg41393#msg41393 . 

Essentially, if you can engineer a reflector with high efficiency and place it so that as much light as possible hits the water's surface of the tank, then you can, with some certainty, use W/m2 to estimate PPF at specific water depths. 

So, to summate by example: if you have two 30 W T8 tubes they are emitting approximately 60 PAR. If you have a good reflector that can focus all the light into the tank (which is impossible but lets just pretend) which is 36 x 12 inches in surface area you will get 222 PPF (PPF = PAR/(0.9 x 0.3 m)). Assuming 70% of the light actually enters the water, this will mean you will have about 99 PPF at 15 inches of _water _depth (not _tank _depth). More than enough for Glosso and HM and unless you have ample CO2 and nutrients you will get an algae soup. Without reflecors the value would be closer to 30-40 PPF which attests to the old adage that 2 full length tubes are enough to grow just about any plant.

* The issue here is that light moving through water is subject to the law of attenuation, not the inverse square law, and there is significant internal reflection of the light moving from the water to the glass. Light out of a fishtank follows the inverse square law just fine meaning the higher your lamps above the tank the less your photon density becomes with distance from the source.


----------



## jeffkrol

tyronegenade said:


> Using this data, and Tom Barr's PPF data for actual planted aquariums and scientific journals for attenuation coefficients*
> The major factors (that will vary with each aquarium setup) are the turbidity of the water (the more light absorbing dissolved solids the more light is absorbed with depth), the amount of light lost to reflection due to surface disturbance or angle of lamp to water (90% of the light hitting the water at 60o is reflected and it gets worse the shallower the angle). You need the lamps as close to the water as possible to keep the angle of incidence steep.
> 
> * The issue here is that light moving through water is subject to the law of attenuation, not the inverse square law, and there is significant internal reflection of the light moving from the water to the glass. Light out of a fishtank follows the inverse square law just fine meaning the higher your lamps above the tank the less your photon density becomes with distance from the source.


I'm not following this.. Seems the inverse square law "applies" and you have an added component(s) as you have mentioned.. adsorption, scattering, refraction ect.. 

As for attenuation.. specific wavelengths are adsorbed at different depths BUT this is not realty applicable at what we are using (like 2 ft.) 









for fun 
http://scholarsarchive.library.oreg...ASAbsorptionAttenuationVisible.pdf?sequence=1


----------



## tyronegenade

Jeff, that graph is very interesting as it would speak against my attenuation coefficients:
red = 1.007
orange = 0.755
yellow = 0.336
green = 0.226
blue = 0.132
violet = 0.216
These have been double checked against various sources and hold up well, especially in water rich in polyphenolics (like our fishtanks and very much unlike the open ocean). The article will make for good reading later on when I have the time...

As much as 50% of red light is lost in 2 foot of water. The attenuation coefficient for red light is 1.007. Do the math. In addition, visit the data I link to. A model of attenuation fits the data nearly perfectly, giving an R^2 of 0.999979*. The inverse square law doesn't fit at all. 

*This good statistical fit doesn't necessarily mean that we are observing attenuation in a pure sense. I suspect that the reality is a combination of inverse square, internal reflection and attenuation. If this suspicion is correct then wider tanks should have higher attenuation coefficients than narrow tanks. I haven't had the chance to do the experiment and test this hypothesis. But, for now, the math works _as if_ attenuation is the major factor.

I don't have the time to argue for my model. I suggest that people test it by experiment and then let me know where it is wrong. As an experimental scientist I don't need my theory to be correct, I just need it tested. I expect the assumptions and data used to arrive at the estimates to be revised but so far the attenuation model holds up to scrutiny and gives a very good estimate of how much light intensity is lost with depth. The major holes are for how much light actually gets into the water column, which has more to do with reflector design than anything else. The math I show on the other site is for a moderately efficient reflector design and most of the light actually entering the aquarium.

This is a simple model that can be used to guesstimate the amount of power you need over your aquarium and if it has failings they will quickly show in experiments where the model is put to the test.


----------



## jeffkrol

Well to be perfectly honest, this is much more your field than mine.. So I give you a bit more that corresponds and also questions those findings..
http://www.cen.ulaval.ca/warwickvincent/PDFfiles/137.pdf

Unfortunately it doesn't go far enough in red data.. 

You may want to start w/ this one.. 

to be clear, I'm certainly not saying your wrong and since you state:


> I suspect that the reality is a combination of inverse square, internal reflection and attenuation.


That pretty much puts us on the same page.. 

pay to play article:
http://link.springer.com/article/10.1007/s10750-012-1084-2
http://link.springer.com/article/10.1007/s10333-010-0207-5

I have no doubt that between the inverse square rule and attenuation you lose light, and specific bandwidths by depth....

This is probably the best.. go to pg 10.. Pretty close to your data.. except:
They throw in a red absorption by chlorophyll for the attenuation in red as a parameter..
http://www.serc.si.edu/labs/phytoplankton/pdfs/DiagTool.pdf


----------



## Greystoke

I think Tyrone was correct in the first place, because the "inverse square law" implies that light is propagated in accordance with that law and without attenuation.
The way he described the light's propagation, the "inverse square law" did not apply.
Just my 











Regards
Cor


----------



## jeffkrol

Greystoke said:


> I think Tyrone was correct in the first place, because the "inverse square law" implies that light is propagated in accordance with that law and without attenuation.
> The way he described the light's propagation, the "inverse square law" did not apply.
> Just my
> 
> 
> 
> 
> 
> 
> 
> 
> 
> 
> 
> Regards
> Cor






> The fact is that the processes of intensity reduction by distance and by attenuation do not operate exclusively in many situations involving exposure to photons. It is necessary to consider both processes in order to account properly for the reduction in primary photon intensity. Note that I have referred several times to primary photons—i.e., those emitted directly by the source. In addition to these, it is often necessary to account for the effects of secondary photons that arise as a consequence of interactions of the primary photons in the media through which the primary photons travel. Compton-scattered photons are among the most important in this regard. The impact that these secondary photons have on increasing the dose rate at the point of interest may be substantial and is often accounted for in calculations by the use of a buildup factor that represents the factor by which the primary photon dose (rate) is increased by these secondary radiations. If you are interested in a more detailed discussion of this process, see the information available at this link on the HPS website.
> In summary, we do not generally have the option of choosing either distance or attenuation as an approach to calculating dose rate from a source; we must consider both reduction of intensity by increasing distance from the source and reduction by attenuation in any media between the source and dose point. It is only in cases when one of these reduction mechanisms becomes insignificant compared to the other that it is appropriate to neglect the lesser effect.
> I hope this clarifies the situation for you.
> George Chabot, PhD, CHP


http://hps.org/publicinformation/ate/q9866.html

Energy is energy..


----------



## Greystoke

I'm no match for that eloquent explanation. I submit


----------



## jeffkrol

Greystoke said:


> I think Tyrone was correct in the first place, because the "inverse square law" implies that light is propagated in accordance with that law and without attenuation.
> The way he described the light's propagation, the "inverse square law" did not apply.
> Just my
> 
> 
> 
> 
> 
> 
> 
> 
> 
> 
> 
> Regards
> Cor


Well he is correct, to a degree. I should attempt to better explain my "thinking" on this.

The light source IF completely perpendicular to the water surface (and ignoring reflections, refraction), would be almost completely at the mercy of attenuation by absorbance from "things"...

Problem as I see it, light angles are never perfectly perpendicular (and is more the exception than the rule). Even though they are almost never true point sources either, most will "obey" the inverse square rule laws.
Water won't "focus" light to a perpendicular beam either. More to the contrary or at the least a wash,, bent here bent there.. 
Then add scattering due to particles, waves, ect. 
As to attenuation, something to consider is IF there is a large loss of red you must consider where it went (actually w/ any particular bandwidth, but I am red obsessed.. ) 
IF it is mostly absorbed by photosynthetic pigments.. this is a "good thing" and attenuation of red is not a negative factor..unless it is being absorbed by suspended algae in your tank..  

I prefer to, right or wrong, break the light column down to
1)losses by the inverse square rule 
2) losses due to interface effects (angle of incidence, reflection,refraction, and scattering by particulates) 
3)attenuation of various frequencies chemicals (including water) 

There certainly may be more attenuation than I have generally given credit to, but again, some is good.. i.e red absorption by chlorophyll, UV absorption by water and IR absorption by same.. ect.. 

Which one is most important?? Well I don't think you can ignore any.. 
but then again, just buy brighter lights.. 

quantifying anything in complex environments is always a compromise, but I suspect you can "guessitimate" it using either inverse square or some generalized attenuation equation as well..

Though that quote deals w/ x-rays this line :


> It is only in cases when one of these reduction mechanisms becomes insignificant


is key.. Does the inverse square law become "insignificant"??? I argue it does not..  Neither is attenuation "insignificant"...  

http://www.pmodwrc.ch/newrad2005/pdfabstracts/Newrad044.pdf


----------



## Hoppy

Tyrone is incorrect in his first assumption: light bulbs don't emit a certain PAR per watt. PAR is not a correct parameter for light emission. I don't think there is a standard parameter that fits the role that lumens plays with light as seen by humans. With lumens, the equivalent of PAR is lux, but there is no equivalent that I know of for lumens when you are talking PAR. PAR and lux are measurements of light intensity at a specific point, not the total light emitted by a source.

The inverse square rule is a geometric rule, and it makes no difference what kind of light or other radiation you are dealing with. The only exception would be for light collimated into a perfect beam, with no spread as the light travels over a distance. The closest thing to that would be a perfect laser. Once you have the most minute spread vs distance the inverse square rule applies, so it even applies to real world lasers. A laser aimed at the moon produces a many miles wide beam at the moon, and that beam width follows the inverse square rule.


----------



## lochaber

just to back up Hoppy's post:

http://what-if.xkcd.com/13/


----------



## AquaAurora

I have a few questions after reading/viewing graphs.

First off, with CFL bulbs: it I have a 4 foot long tank, and want low light (setting up the light to match distance and bublb/equipment for low-light in graph) how many lights would I actually need to cover the 4 foot long distance? 2? 4?

For LED: if I get 2 sets of Mareinland doublebright "24 (one for each side of a 4ft long) will that par reading now be equal to whats shown for the 48" mareinland double brights on the graph?

I hope someone can answer these questions for me ^^''

*Edit:also a question for Hoppy: for the Mareinland double bright led lights, you list sized 24" and 48" when you buy them there's two sizes that overlap, 18-24 and 24-36 / 36-48 and 48-60, which ones did you use for the test?*


----------



## Hoppy

AquaAurora said:


> I have a few questions after reading/viewing graphs.
> 
> First off, with CFL bulbs: it I have a 4 foot long tank, and want low light (setting up the light to match distance and bublb/equipment for low-light in graph) how many lights would I actually need to cover the 4 foot long distance? 2? 4?


The number needed depends on the size of the dome type reflectors you use. The larger the diameter, the more area of the tank the light covers. It is very hard, if it is even possible, to get two bulbs over one area, with those dome reflectors, so you need a bulb of a high enough wattage to light up the area it covers to the PAR you want, at the distance you will have the lights.


> For LED: if I get 2 sets of Mareinland doublebright "24 (one for each side of a 4ft long) will that par reading now be equal to whats shown for the 48" mareinland double brights on the graph?
> 
> I hope someone can answer these questions for me ^^''
> 
> *Edit:also a question for Hoppy: for the Mareinland double bright led lights, you list sized 24" and 48" when you buy them there's two sizes that overlap, 18-24 and 24-36 / 36-48 and 48-60, which ones did you use for the test?*


I didn't test those lights. The data is from others. The chart is for the lower of the two numbers. The higher number means the supporting "bars" on the ends of the light will stretch out enough to fit on that larger length tank. But, the LEDs will only be over the smaller length of the tank.


----------



## AquaAurora

Hoppy said:


> The number needed depends on the size of the dome type reflectors you use. The larger the diameter, the more area of the tank the light covers. It is very hard, if it is even possible, to get two bulbs over one area, with those dome reflectors, so you need a bulb of a high enough wattage to light up the area it covers to the PAR you want, at the distance you will have the lights.
> 
> 
> I didn't test those lights. The data is from others. The chart is for the lower of the two numbers. The higher number means the supporting "bars" on the ends of the light will stretch out enough to fit on that larger length tank. But, the LEDs will only be over the smaller length of the tank.



Thank you very much for the clarification ^^


----------



## Greystoke

Hoppy said:


> Tyrone is incorrect in his first assumption: light bulbs don't emit a certain PAR per watt. PAR is not a correct parameter for light emission. I don't think there is a standard parameter that fits the role that lumens plays with light as seen by humans. With lumens, the equivalent of PAR is lux, but there is no equivalent that I know of for lumens when you are talking PAR. PAR and lux are measurements of light intensity at a specific point, not the total light emitted by a source.


I'm not entirely with you Hoppy.
Surely the total emission of Photosynthetic Active Radiation from any light source has a name?


----------



## Hoppy

Greystoke said:


> I'm not entirely with you Hoppy.
> Surely the total emission of Photosynthetic Active Radiation from any light source has a name?


No, as far as I know, it doesn't have a name. Nor is there any reason for it to have a name. If you want the total emission from a bulb, it is usually available in lumens, but there is no correlation between lumens and PAR. PAR depends on reflector design, if one is used, on ballast design (for fluorescent bulbs), on distance from the bulb, and on absorption of light between the bulb and where the measurement of PAR is made. PAR is intended only for use in plant growing - it is the usable light striking the plant, per unit area of the plant.


----------



## Greystoke

Hoppy said:


> No, as far as I know, it doesn't have a name. Nor is there any reason for it to have a name. If you want the total emission from a bulb, it is usually available in lumens, but there is no correlation between lumens and PAR. PAR depends on reflector design, if one is used, on ballast design (for fluorescent bulbs), on distance from the bulb, etc. . .


That is difficult to accept. The PAR emission has to come from somewhere, and Lumen only refers to the visible portion of the emitted light. The bulb that emits PAR light has an independent quality that creates it, just like the visible light.

As far as I am concerned . . . 
These bulbs radiate visible light, ie:±450 - 650nm, spectrally filtered to match the sensitivity of human eyes, and quoted in Lumen, and . . .
"PAR" light,calculated from the bulb's straight spectrum between 400 - 700nm, and quoted in ?????.


----------



## lochaber

I think the units that are typically used for PAR are micromoles of photons (just those of a certain wavelenght) per squaremeter per second. So for that, surface area is an integral part of the unit.

I imagine you could find a number for the absolute number of micromoles of photons (again, just the photosynthetically active ones) emitted per second for a give light source.

I'm not sure how useful that would be... If you had a regular bulb, you might be able to calculate the surface area of a sphere with a radius equal to the distance twixt your light and substrate, and then figure out what fraction of that sphere's surface area is equivalent to your tank foot print (or a cylinder for fluorescent tubes) to get an idea of about how much radiation your tank is getting.

I think that's going to be much more work though, as even with a perfectly uniform spherical distribution, the center of the tank would have a higher PAR then the surrounding area. To further complicate things, it seems like a lot of light sources are somewhat directional in their output, which would just make that sort of calculation even messier. I'm pretty sure it would be far easier (and more accurate) to just set up the light and take some readings using the typical PAR unit.


----------



## Hoppy

Greystoke said:


> That is difficult to accept. The PAR emission has to come from somewhere, and Lumen only refers to the visible portion of the emitted light. The bulb that emits PAR light has an independent quality that creates it, just like the visible light.
> 
> As far as I am concerned . . .
> These bulbs radiate visible light, ie:±450 - 650nm, spectrally filtered to match the sensitivity of human eyes, and quoted in Lumen, and . . .
> "PAR" light,calculated from the bulb's straight spectrum between 400 - 700nm, and quoted in ?????.


As far as I know, neither lux (or lumens) or PAR can be calculated from any other parameters of a bulb, or even a bulb plus reflector at a specific distance. Those parameters are measured to determine their values. It is traditional to specify the lumens emitted by a bulb or other light source, but no tradition says that the total micromols of photons per second should be specified for light sources intended to be use for plant growth. When measuring lux accurately, a light sensor which has a filter that matches the measured spectrum to typical human eye sensitivity is used. In reality, inexpensive lux meters use filters that emphasize the green light, and reduce other light, but don't even attempt to match human eye sensitivity.


----------



## jeffkrol

Greystoke said:


> I'm not entirely with you Hoppy.
> Surely the total emission of Photosynthetic Active Radiation from any light source has a name?


Fun w/ names..



> Photosynthetic Photon Flux Density (PPFD)
> 
> Photosynthetic Photon Flux Density (PPFD) is a unit of measure to express
> 
> the light quantum in photons of solar energy (specific to wavelength)
> 
> related specifically to photosynthesis and is measured with a quantum meter
> 
> in units called micro-moles
> 
> 
> 
> The Photosynthetic Photon Flux Density (PPFD) calculation is:
> 
> mol m-2 s-1 (micro-moles of photons per meter squared, per second)





> LUX and Lumens
> The *lumen* (symbol: *lm*) is the SI derived unit of luminous flux, a measure of the total "amount" of visible light emitted by a source. Luminous flux differs from power (_radiant flux_) in that luminous flux measurements reflect the varying sensitivity of the human eye to different wavelengths of light, while radiant flux measurements indicate the total power of all electromagnetic waves emitted, independent of the eye's ability to perceive it. A lux is one lumen per square meter.



PPFD has a TIME component... 

Furthermore.. 



> PAR is defined in terms of photon (quantum) flux, specifically, the number of moles of photons in the radiant energy
> between 400 nm and 700 nm. One mole of photons is 6.0222 x 1023 photons (6.0222 x 1023 is Avagadro’s Number).
> The Photosynthetic Photon Flux Density (PPFD), i.e., the photon irradiance, is expressed in moles per square meter
> and per second (formerly, Einsteins per square meter and per second).
> There is not a general conversion factor between photon measurements and energy or light measurements for broad
> band radiation. However, a specific conversion factor can be determined for a given spectral power distribution, e.g.,
> a particular light source. This is of practical value because conventional lighting calculation techniques can be used
> for design of plant growth areas and because color corrected light or illuminance meters can be used to measure
> PAR values. Some plant scientists want a conversion for the photon flux in the 400 nm to 800 nm band although it is
> not the standard PAR metric (see CIE Publication 106, Section 8, 1993); this conversion also has been included.


SEE chart.. 
http://openwetware.org/images/e/e8/Conversion_lux.pdf



> The Photosynthetically Active Radiation (PAR) measure of radiant power is important in evaluating the effect of light
> on plant growth. In 1972 it was shown by K. McCree (Agric. Meteorol., 10:443, 1972) that the photosynthetic
> response correlates better with the number of photons than with energy. This is expected because photosynthesis is
> a photochemical conversion where each molecule is activated by the absorption of one photon in the primary
> photochemical process.


----------



## Greystoke

Accepted,

But if you know the spectrum of the bulb, it is actually fairly easy to calculate the total Photosynthesis Active Radiation it emits.

Isn't that all we need to know?
All you then need to work out is how much of the bulb's light hits the water surface in order to determine how many watt to install, an away you go.
No need for expensive PAR meters.


----------



## jeffkrol

Greystoke said:


> Accepted,
> 
> But if you know the spectrum of the bulb, it is actually fairly easy to calculate the total Photosynthesis Active Radiation it emits.
> 
> Isn't that all we need to know?


Er.. not really.. Say I have a 660nm LED.. That band is 100% PAR.
And I put it on the moon to shine in my tank... How much PAR on the floor of that tank? 
Spectrum is not enough..(sorry just thought that was cute)


Greystoke said:


> All you then need to work out is how much of the bulb's light hits the water surface in order to determine how many watt to install, an away you go.
> No need for expensive PAR meters.


how would you do that without a meter of some kind, considering all the geometric variables of the light and housing, electrical variability i.e line load changes, aging of phosphors, manufacturing variability.. ect, ? Couple that w/ diffraction, "attenuation", refraction and reflection and , at best, you are really poorly guesstimating...


----------



## Greystoke

A bulb's spectrum is usually given in energy emitted per wavelength. The total energy equals the power in Watt of the bulb.
Based on that you can calculate accurately how much PAR is emitted at that wavelength.

METHOD USED:

1. Digitize the published spectrum at suitable values of wavelength and rebin to a small wavelength step (5 nm). 

2. Numerically integrate the spectrum in sections of 5nm, using Simpson's Rule, with the wavelengths in multiples of 5 nm (the 400nm mark = the integral from 395nm to 405nm, etc . . . ).

3. The total integral is obtained by adding-up all the individual sub-integrals, getting the total power P0 in relative units. 

4. Normalize the digitized spectrum ordinate scale by dividing the relative values by P0. This gives the bulb's spectrum in percentages of the applied input power ("unity" spectrum), assuming that the conversion efficiency from electrical to electromagnetic energy is 100%. 

5. Multiply the unity spectrum by the eye photopic curve (normalized to unity peak). Integrate the result over the same wavelength range used above, and multiply the resulting integral by 683 lumens. This gives the theoretical maximum lumen/Watt output of the bulb. 

6. Divide the bulb's rated lumen/Watt output by this theoretical maximum lumen/Watt output . This gives the overall efficiency factor. 

7. Multiply the unity spectrum obtained above by the efficiency factor. This converts power input into radiation output.

8. Convert the spectrum to µE/sec/nm/Watt using the appropriate physical relation and constants (µE/sec = power in Watts X wavelength in nm x 8.36 10-3). 
Note:
"Einstein" is a unit of radiance. A whole Einstein is defined as 1 mole of photons. One mole is 6.02x10^23 atoms (Avogadro's number). The unit used for PAR radiance is a millionth of an Einstein per second, or 6.02x10^17 photons per second, ie: the microEinstein (µE).
Note, however, that the Einstein is not an official SI unit of measure. 

9. Integrate the µE/sec/nm/Watt spectrum in the 400-700 nm range. The result is the bulb's PAR/Watt measure.


Your "moonlight" example is actually fairly easy:
If the bulb radiates equally in all direction, all you do is use the inverse square law (ISL) to work out what percentage of the bulb's radiation hits the water surface of your tank. I follows that: PAR intensity at the water surface = ISL x total emitted PAR divided by water surface area.


----------



## jpappy789

Personally...I'm not going to do integers to figure out PAR :icon_eek:


----------



## Greystoke

jpappy789 said:


> Personally...I'm not going to do integers to figure out PAR :icon_eek:


Of course not, why should you? This is the manufacturer's duty.

However, seeing that there is no legal requirement (yet), someone should do it just for our sake.

I've done this dozens of times. Luckily lots of the spectra are similar (particular for LEDs) so you can use a representative spectrum as a generic for short cuts.
Lots of bulb's with the same Kelvin ratings have similar spectra.


----------



## Hoppy

Greystoke said:


> A bulb's spectrum is usually given in energy emitted per wavelength. The total energy equals the power in Watt of the bulb.
> Based on that you can calculate accurately how much PAR is emitted at that wavelength.
> 
> METHOD USED:
> 
> 1. Digitize the published spectrum at suitable values of wavelength and rebin to a small wavelength step (5 nm).
> 
> 2. Numerically integrate the spectrum in sections of 5nm, using Simpson's Rule, with the wavelengths in multiples of 5 nm (the 400nm mark = the integral from 395nm to 405nm, etc . . . ).
> 
> 3. The total integral is obtained by adding-up all the individual sub-integrals, getting the total power P0 in relative units.
> 
> 4. Normalize the digitized spectrum ordinate scale by dividing the relative values by P0. This gives the bulb's spectrum in percentages of the applied input power ("unity" spectrum), assuming that the conversion efficiency from electrical to electromagnetic energy is 100%.
> 
> 5. Multiply the unity spectrum by the eye photopic curve (normalized to unity peak). Integrate the result over the same wavelength range used above, and multiply the resulting integral by 683 lumens. This gives the theoretical maximum lumen/Watt output of the bulb.
> 
> 6. Divide the bulb's rated lumen/Watt output by this theoretical maximum lumen/Watt output . This gives the overall efficiency factor.
> 
> 7. Multiply the unity spectrum obtained above by the efficiency factor. This converts power input into radiation output.
> 
> 8. Convert the spectrum to µE/sec/nm/Watt using the appropriate physical relation and constants (µE/sec = power in Watts X wavelength in nm x 8.36 10-3).
> Note:
> "Einstein" is a unit of radiance. A whole Einstein is defined as 1 mole of photons. One mole is 6.02x10^23 atoms (Avogadro's number). The unit used for PAR radiance is a millionth of an Einstein per second, or 6.02x10^17 photons per second, ie: the microEinstein (µE).
> Note, however, that the Einstein is not an official SI unit of measure.
> 
> 9. Integrate the µE/sec/nm/Watt spectrum in the 400-700 nm range. The result is the bulb's PAR/Watt measure.
> 
> 
> Your "moonlight" example is actually fairly easy:
> If the bulb radiates equally in all direction, all you do is use the inverse square law (ISL) to work out what percentage of the bulb's radiation hits the water surface of your tank. I follows that: PAR intensity at the water surface = ISL x total emitted PAR divided by water surface area.


This can give you the lumens emitted by the bulb, or, if you prefer, the micro moles per second of photosynthetically active radiation emitted by the bulb, but without information about the reflector being used, or, for LEDs, the optics being used, you can't determine PAR at a specific distance from the bulb this way. PAR varies with distance from the source of light, it is not a fixed parameter for a given bulb. And, the amount of light striking the area where you want to know the PAR depends heavily on the reflector characteristics. And, there is no fixed relationship between the watts consumed by the light source and the PAR produced by the source. That depends on the efficiency of the bulb/LED in converting electricity to light energy, which can vary widely.


----------



## Greystoke

Hoppy said:


> . . . And, the amount of light striking the area where you want to know the PAR depends heavily on the reflector characteristics. And, there is no fixed relationship between the watts consumed by the light source and the PAR produced by the source. That depends on the efficiency of the bulb/LED in converting electricity to light energy, which can vary widely.


The efficiency of a reflector can be estimated, or measured. For LEDs you don't need reflectors and the optics (lenses) have known characteristics.
What you need to establish is how much - as a percentage - of the total radiated light hits the water surface, and that doesn't have to be very accurate. 10% errors are fine.

Also:
The efficiency of ALL our light sources are well known and documented


----------



## jeffkrol

Greystoke said:


> A bulb's spectrum is usually given in energy emitted per wavelength. The total energy equals the power in Watt of the bulb.
> Based on that you can calculate accurately how much PAR is emitted at that wavelength.
> 
> METHOD USED:
> 
> 1. Digitize the published spectrum at suitable values of wavelength and rebin to a small wavelength step (5 nm).
> 
> 2. Numerically integrate the spectrum in sections of 5nm, using Simpson's Rule, with the wavelengths in multiples of 5 nm (the 400nm mark = the integral from 395nm to 405nm, etc . . . ).
> 
> 3. The total integral is obtained by adding-up all the individual sub-integrals, getting the total power P0 in relative units.
> 
> 4. Normalize the digitized spectrum ordinate scale by dividing the relative values by P0. This gives the bulb's spectrum in percentages of the applied input power ("unity" spectrum), assuming that the conversion efficiency from electrical to electromagnetic energy is 100%.
> 
> 5. Multiply the unity spectrum by the eye photopic curve (normalized to unity peak). Integrate the result over the same wavelength range used above, and multiply the resulting integral by 683 lumens. This gives the theoretical maximum lumen/Watt output of the bulb.
> 
> 6. Divide the bulb's rated lumen/Watt output by this theoretical maximum lumen/Watt output . This gives the overall efficiency factor.
> 
> 7. Multiply the unity spectrum obtained above by the efficiency factor. This converts power input into radiation output.
> 
> 8. Convert the spectrum to µE/sec/nm/Watt using the appropriate physical relation and constants (µE/sec = power in Watts X wavelength in nm x 8.36 10-3).
> Note:
> "Einstein" is a unit of radiance. A whole Einstein is defined as 1 mole of photons. One mole is 6.02x10^23 atoms (Avogadro's number). The unit used for PAR radiance is a millionth of an Einstein per second, or 6.02x10^17 photons per second, ie: the microEinstein (µE).
> Note, however, that the Einstein is not an official SI unit of measure.
> 
> 9. Integrate the µE/sec/nm/Watt spectrum in the 400-700 nm range. The result is the bulb's PAR/Watt measure.
> 
> 
> Your "moonlight" example is actually fairly easy:
> If the bulb radiates equally in all direction, all you do is use the inverse square law (ISL) to work out what percentage of the bulb's radiation hits the water surface of your tank. I follows that: PAR intensity at the water surface = ISL x total emitted PAR divided by water surface area.


and this is "easier" than a meter placed in the tank????? 

Let's face it even "trusting" manufacturer specs in a commercial product is a "leap of faith".... garbage in garbage out comes to mind... 

what were the parameters when plotted.. What bin? What temp? What day of the week were they manufactured? Same part supplier? Same phosphors, what was the humidity of the test air? ect.... list is almost endless.

Number one is "problematic" to say the least.
to add to this:
what is the phosphor decay after 2 months? How "easy" is that to figure out.. What about "dimming" say I run at 80%. (which driver, how efficient, how well "stepped")..how much is the light energy effected by LED temps in the "real world" ect.


----------



## Greystoke

Computers do the work. It's no sweat at all.

Now why must I buy an expensive meter, which - in the case of LEDs - I may need once in ten years.
I assure you that I can think of much better ways to spend my money. 

Besides, some manufacturer's data may not be accurate, but they are - generally - not intended to be misleading. You can surely trust the respected makes' data to be accurate within a few percent.

If I can work out a bulb's parameter, based on manufacturer's data that turns out to be with a 10% error margin, then I will call that "PERFECT".


----------



## jeffkrol

Greystoke said:


> Computers do the work. It's no sweat at all.
> 
> Now why must I buy an expensive meter, which - in the case of LEDs - I may need once in ten years.
> I assure you that I can think of much better ways to spend my money.
> 
> Besides, some manufacturer's data may not be accurate, but they are - generally - not intended to be misleading. You can surely trust the respected makes' data to be accurate within a few percent.


you have way more faith in manufacturers than I do. Admittadly most would not intentionall mislead, unless of course it was only semi-intentional, like picking the "best of" for the test..lies, damned lies, and statistics.. 

Also the other point was not to use an "expensive" meter ..at least in comparison to all things considered, esp. if it were saltwater..or the more exotic freshwater livestock.. 

If you want to really save money and hassles, completely ignoring the whole PAR subject is an option..

As to me, and others who use "generic" parts for DIY builds, there is not a"manufacturers option"... and buying "off the shelf" would be because I had done "due diligence" and have already decided, allowing the "test of time" to tell me if it was correct or not...

to put a real face on this.. take what I'm currently doing.. I'm programming a ramp up ramp down of 3 color channels during the day w/ 3 different ramp start points . IF I really was inclined, I'd like to know my PAR per unit time, and adjust as I deem fit by changing one or 2 or 3 colors at specific points in time.
NO amount of manuf. data (IF I had any) would help in this, in an easy straight forward way. Yes given spectral analysis and a plotting of that vs power then combining all three I could "theoretically" calculate PAR and it might be "theoretically" correct but how would you know???? You still need sampling to verify the math.. Then and only then can things be changed w/ expected results.. Until something get different... Driver burns out, I get a new one.. How does that change the math. I replace a color w/ a newer chip ect... 

I understand your point but:
1)you still need to verify because somewhere you have assumptions. Granted that can also apply to a meter. So the 2 go hand in hand. I know of little science where the math doesn't have to be proven by real world sampling or "observation".. And even if accepted one still looks for "proof" 
2) Given the facts of one, sampling at the point of interest will always hold more validity, if only psychological at the least..


----------



## Greystoke

I wholeheartedly agree with that philosophy. Just remember: If your fish and plants do well, then you must have done most things right.


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## DKRST

After reading all the threads above, it's just easier to check the levels with my PAR meter than get a headache from the calculations, especially since PAR changes over the life of a fluorescent bulb.... 

The theoretical PAR output calculation is a nice academic discussion but, to me, not of particular _functional _use given the variables in any given tank setup.


----------



## Greystoke

Owning a PAR meter is about as necessary as owning a Lux meter. The only reason why you have a PAR meter is because the manufacturer - contrary to luminous output - is not legally required to publish PAR parameters.

If the total PAR output of a bulb was known/published, you wouldn't really need a PAR meter.

All I do to help my friends (all without PAR meters) is provide them with PAR figures based on the published spectrum of the bulb they intend to purchase.
And its no sweat at all. The computer does the work.


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## jeffkrol

Just thought this was interesting .. from our reef brethren:



> They aren't that expensive really. I bought an Apogee 200 PAR meter and it is about $400.00.
> 
> That isn't much to pay when you consider that you will be able to dial your lights in the first time with no guessing.


http://www.reefcentral.com/forums/showthread.php?t=2335714

For fun... 


> *SENEYE REEF MONITORING SYSTEM AND PAR METER - WILL SHIP INTERNATIONALLY!*
> 
> *PAR+LUX+KELVIN+AMMONIA+PH+TEMP ALL IN ONE DEVICE!*
> 
> Price:
> US $169.00


Meters AND computers... marvelous..

http://www.seneye.com/


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## Hoppy

You can also buy a very usable PAR meter for $60, which isn't peanuts, but it also won't break the bank for most people who can afford to be in this hobby. Just search the For Sale forum.

Where theoretical calculations, like Greystoke is referring to, are most valuable is for determining what the form of the equation relating PAR to a light fixture's parameters is. Once you can figure that out, you can get a few data points and use those to develop a very accurate equation/chart that tells you the PAR for any lighting scheme. For example, once you know that light intensity follows the inverse square rule, you can easily determine what the PAR is at any distance if you know the PAR at one distance, providing all of those distances are much longer than any dimension of the light source. Add a few more data points for PAR at shorter distances, and you can predict the PAR at any distance, short or long. This is easiest if you always plot your measured data on log-log graph paper.


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## Greystoke

It’s nice to see efforts to understand this argument, however . . . 
even $60 for a PAR meter is still a lot of money in South African currency as that equals about a week’s groceries.
I only know a handful of people in the whole of South Africa that own a PAR meter.

PAR meters were developed – back in the 70’s – when it was found that photosynthesis was better predicted by counting photons than using foot-candle and lux measurement meters.

For comparison: The power in Watt of a single photon equals h.c/λ/s (in which h= Planck' s constant (6.63×10⁻³⁴ m².kg/s), c = Velocity of Light (299792458 m/s) and λ = The Wavelength in m, which at 555nm works out to: 3.58x10⁻¹⁹ Watt per photon. The PAR value for that very same photon would be: 1.66x10⁻¹⁸ 

Using this relationship it was found that the average fluorescent light used in our hobby returns *one PAR for every Watt* installed.
(_The true relation varies by ± 10% for full spectrum tubes._)

This number provides a means to determine how much light actually should hit the water surface. That is if you know your reflector efficiency. (_Try this: Reflector Efficiencies_)

Unfortunately, we are completely in the dark about how much light finally reaches the substrate. We know that it depends on the wavelength, the color of the water, the clarity and how many objects and plants inhibit the light propagation.
However - when completely lost – the approximate loss through the water column can be measured with an ordinary LDR (Light Dependant Resistor) and a multi meter.

So, in my opinion we shouldn’t be too pedantic about exactitudes. Our hobby is not that critical. If you can estimate parameters to within 10% accurate (Lumen or PAR), then that's just perfect. And if a manufacturer can give a representative spectrum of his lamp, then it's possible to work out most parameters to within that margin of error.

Never mind meters. Watch your tank. If the plants and fish do well, then you must be doing things right.


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## audioaficionado

I dunno... it's kinda nice to be able to measure the light levels with an inexpensive PAR meter so we can all compare notes more precisely in the same units. If it was a simple as a conversion factor, everyone would be using the cheapest light meter they could get their hands on. Compared to other equipment expense aspects of this hobby, US $60 is very reasonable.


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## carpalstunna

Just ordered a hoppy meter. Plan to do a lot of testing


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## Greystoke

audioaficionado said:


> I dunno... it's kinda nice to be able to measure the light levels with an inexpensive PAR meter . . .


I agree . . . A PAR meter is nice to have. :icon_wink


----------



## zanguli

Hi members,
how are you ?

First thanks to Hoppy to bring out this chart that is very useful. I have discover this forum by this thread, an expert member of an other forum linked me this thread that is very very interesting. so every one thanks for you input in this topic.
after reading the 52 pages of the old thread (that was very long but food for brain) I am a bit confuse now haha.
Let me explain.
Tank : 90x45x50 cm 
Light : NA SunFluor 4x36W osram PC hanging at 20" from the substrate
reflector is a very high polished aluminum.
the tanks is only 3 weeks old so I turn on only two bulbs.
Pressurize C02

After reading all the topic I have discover that PC gives a lower PAR reading than T5HO.

My concern is that maybe with only two PC bulb of 36 W at that height I will be too low in PAR (Tom Barr said in this topic that the limit range for most of the plant (not low light plant) will be 25-30).
So I am just afraid that maybe with this configuration I might be too short ? 

If I follow the graph with one PC bulb at 20" I will have a PAR +/- 20 so for two I will have PAR 40, Is that right ?
In fact I would like to grow a HC carpet (I have fail many time with it) I truly know that HC is a CO2 lovers and need good distribution down to the carpet to achieve a good carpet, but with that amount of light am I in the good zone to grow it, am I not too short on light? 
Would you advice me to stay in this configuration until the tank is mature and plant have made the transition, or I should turn the third bulb for the HC. I don't want to push the too high for now to be sure that HC will do the transition and not melt due the higher demand of CO2 that stronger light will thrive.

Sorry if my post is a bit confuse but it reflect my state of mind hahaha.
I wanted also to apologies if I have mad grammatical and other language mistakes, but english os not my language.

thank you very much for you help.
Regads
Zanguli


----------



## zanguli

Hi members,
no answer about my request ? If someone could kindly answer me that would be good 

cheers


----------



## madpiano

I have been reading this thread with interest. Although I no longer own a fish tank (sad), I am intenting of aquiring a tank-hood next year to grow my tomato and chili seedlings. So I am actually more interested in the behviour in air. Lights for fish tanks are just way cheaper than lights at the garden centre made for plant growing. 
Thanks for making all this info available!


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## paronaram

"...tomato and chili seedlings..." :hihi: :icon_wink


----------



## Hoppy

The 36 watt PC bulbs are probably only about half as long as the tank, so if you use two of them, they are probably in one end to end row across the top of the tank. If that is true I think you will want to use all 4 bulbs. A lot depends on the shape of the reflector. If it is shaped so you see an image of the bulbs on each side of them, looking up at the bulbs, so it appears that you have 3 times as many bulbs as you really do, then you might have too much light with all 4 bulbs. If not, you will almost certainly not have enough with only the 2 bulbs.


----------



## zanguli

Hi Hoppy,
thanks for your answer !!
the reflector is a single flat panel of high polished aluminum for the 4 bulbs.
I can see only one image of bulb per real bulb and just at the top of that bulb, so the real bulb cover a bit reflection of this image. So I don't think reflector is doing a great job. 
Even if the bulb is half the length of the tank, all the tank is covered by light.
let me search for a pictures of the light and I post it. light is hanging at 20" from the substrate.

Thanks again for your answer and your time.

best regards
Zanguli


----------



## zanguli

Hoppy said:


> The 36 watt PC bulbs are probably only about half as long as the tank, so if you use two of them, they are probably in one end to end row across the top of the tank. If that is true I think you will want to use all 4 bulbs. A lot depends on the shape of the reflector. If it is shaped so you see an image of the bulbs on each side of them, looking up at the bulbs, so it appears that you have 3 times as many bulbs as you really do, then you might have too much light with all 4 bulbs. If not, you will almost certainly not have enough with only the 2 bulbs.


Here is a pic of the NA Sunled that have the same body than my light but with LED strips. But you can see the aluminum panel. 









And this is the shot of my light 










Like that you can have an idea. 

Cheers


----------



## zanguli

Hi members,
So what do you think I should do with this light configuration ? Should I turn on 4 bulb or with the reflector I have I can go with two than three and at the end 4 bulbs ?? 

Cheers


----------



## dzega

i still dont get HOW can you build a filter that matches photosynthesis spectrum pattern? without such a filter infront of light sensing element in your meter you are only measuring luminous flux converted via math, nothing more.. actually even worse, you might also be measuring infrared heat that has nothing to do with plant growth

what im saying is if particular device does not have protosynthesis spectrum pattern filter infront of it, i can make it read insane numbers of light that actually cant grow anything. one way is to put it under strong pure green LED. the other way is to put it under near/mid infrared emitter. and so on


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## Master Se7eN

Love it! reason 1 why we need changes.... Wait for it....Wait for it....Here is omes...


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## Greystoke

dzega said:


> i still dont get HOW can you build a filter that matches photosynthesis spectrum pattern? without such a filter infront of light sensing element in your meter you are only measuring luminous flux converted via math, nothing more..


Good PAR meters have filters that block light below 400nm and above 700nm, just like a band-pass filter. PUR is yet another matter. However, IF (big "if") the spectrum of the light is known within reasonable limits of accuracy, then the PUR output can be calculated. A good indicator for PUR is the RED/BLUE ratio. It covers the same sections of the light's spectrum.



dzega said:


> . . actually even worse, you might also be measuring infrared heat that has nothing to do with plant growth


I understand that Tunnel growers often discuss the infra red output of their lights. It apparently has a certain influence.


----------



## dzega

I quote PAR definition in the first post: PAR is an acronym for “photosynthetically active radiation” - the radiation (light) that is used by plants for photosynthesis. 

Which basically means that to measure PAR by that definition photosynthesis spectrum curve-like filter is a must on given measuring device. And being microwave engineer I can't imagine how one can produce that filter at home in fifty dollar DIY device. 

Simple band pass filter is not good enaugh since it will pass green light which is not used for photosynthesis. 

the only thing you guys are actually measuring with your devices is relative light loss in aquarium media. And even that is not completely true since water does not block all wavelengths equally

sorry for being an ass


----------



## jeffkrol

dzega said:


> I quote PAR definition in the first post: PAR is an acronym for “photosynthetically active radiation” - the radiation (light) that is used by plants for photosynthesis.
> 
> Which basically means that to measure PAR by that definition photosynthesis spectrum curve-like filter is a must on given measuring device. And being microwave engineer I can't imagine how one can produce that filter at home in fifty dollar DIY device.
> 
> Simple band pass filter is not good enaugh since it will pass green light which is not used for photosynthesis.
> 
> the only thing you guys are actually measuring with your devices is relative light loss in aquarium media. And even that is not completely true since water does not block all wavelengths equally
> 
> sorry for being an ass


Well green light is used, it is just not very efficient.. 
"professional" PAR meter sensor spectrum, red line is an "ideal" sensor (in A research defined sense, but I do agree, and the curves make obvious, there is error no matter what you do):








See more here:
http://www.advancedaquarist.com/2013/2/equipment

See this for my thoughts on a $50 filter/sensor..well more like $70ish, unless you can cut the oversize Baader to use w/ multiple sensors. It is the most expensive part.
http://www.adorama.com/AA2459207A.html?gclid=CKGc3-fOmroCFU8V7AodpxwAGA
http://www.plantedtank.net/forums/showthread.php?t=443073&highlight=
silicone photo diode... 
Baader filter for UV/IR cutoff 
and a inverse filter to Si diode curve

won't be perfect.. but none are..

might as well throw in the expensive Li-cor









Baader filter response:









Si photo diode w/ simulated Baader cutoff applied


----------



## dzega

from provided link i read * PAR=electromagnetic energy between 400 and 700nm (violet to red) per area unit (often 1 square meter) per time unit (usually 1 second)* (and not the actual energy consumed in photosynthesis by plant)
going by this definition you obviously can measure it with relatively simple device.
but then again measuring this way you presume that all wavelengths are equally effectively consumed by plant, which obviously is not true.

still, i do admit this method is better for predicting photosynthesis because it leaves out 'human eye filter curve' introduced in lumen definition.


----------



## dzega

i would like to suggest construction for actual photosynthesis prediction device for diy enthusiasts.
to meet photosynthesis curve we need to divide PAR spectrum in several blocks and adjust each blocks contribution to the summar reading.
easy way to do so looks to me is using different kinds of photoresistors insted of photodiode, because photoresistor itself acts as a filter. 
see pic









the hard(but more accurate) way would be using several photodiodes with selective filters


----------



## Greystoke

dzega said:


> from provided link i read *PAR=electromagnetic energy between 400 and 700nm (violet to red) per area unit (often 1 square meter) per time unit (usually 1 second)*


I suspect that that is Hoppy's preferred definition.
I prefer a simpler one: One PAR equals one micromole of photons between 400 and 700 nm, radiated from a light source point per second.


----------



## dzega

Greystoke said:


> I suspect that that is Hoppy's preferred definition.
> I prefer a simpler one: One PAR equals one micromole of photons between 400 and 700 nm, radiated from a light source point per second.


now i suspect that too.
just needs to change few words to make it right in definition on 1st page:

_the *radiation* (light) *that is used* by plants for photosynthesis. _(means plants absorbed photons)

-->

_the *radiation* (light) *that could be used *by plants for photosynthesis. _(means radiation within specified wavelength)

altho i still might be wrong since English is not my native language


----------



## Sonvar

This is a lot of information to take in and I commend you on the effort you put forth. My question is, how to really utilize this information? Many websites that talk about planted tanks give plant lighting requirements in watts/gallon. I am not sure how to convert the information I have gathered on my research for my tank to the more appropriate information of using PAR's. 
I would like to know more since in my tank certain plants are thriving as others struggle. Im assuming it is a lighting issue, (or at least light penetration to smaller plants.)


----------



## Guest

*Hoppy,*

In my "quest" to find a good balance between light and co2, I hope you can help me with a lighting question. 

Tank: 
24 Inch x 14 Inch x 16 Inch or 60cm x 35cm x 40cm

Lightning
1 x 24w T5 Dennerle Amazon day (6000k) (Bulb is 22 inches long) or 55cm
1 x 24w T5 JBL Tropical Plant (9000k) (Bulb is 22 inches long) or 55cm

Since my tank is 16 inches high (- 1 inch substrate), I estimated from your charts that I had to put my lights higher above my tank to reduce the levels of PAR at the substrate. (Algae investation)

They currently hang on 8,5 inches above the tank. Which would be around 23 Inches from bulbs to substrate. 

Since I was all guestimating and trying to figure out your rocket science method (It is for me and I'm really trying), could you indicate or give some advice if im on the right path to Rome (PAR wise). 

Kind regards,

The Dutchman.


----------



## Dskudera124

tyronegenade said:


> From the data accumulated at http://www.apsa.co.za/board/index.php?topic=4454.0 (in 2010) it is calculated that, on average, you get about 1 PAR/W from tube/fluorescent lamps (T8 & T5). (T5s are only marginally better for output and this is due, mostly, to geometry.) So a 20 W CFL will put out as much PAR as a 20 W T8 tube (because the physics of light emission process is the same). Of course the CFL is all twisted and a lot of light is lost among the twists and turns of the tube (especially as about 30-40% of the light emitting surface is facing another light emitting surface and gets lost by "squishing").
> 
> The major factors (that will vary with each aquarium setup) are the turbidity of the water (the more light absorbing dissolved solids the more light is absorbed with depth), the amount of light lost to reflection due to surface disturbance or angle of lamp to water (90% of the light hitting the water at 60o is reflected and it gets worse the shallower the angle). You need the lamps as close to the water as possible to keep the angle of incidence steep. The quality of your reflector is also critical. With a bad reflector you are probably getting less than 50% of your light into the tank. With no reflector the value is closer to 30%. A model to determine reflector efficiency is available at http://www.apsa.co.za/board/index.php?topic=4379.msg41393#msg41393 .
> 
> Essentially, if you can engineer a reflector with high efficiency and place it so that as much light as possible hits the water's surface of the tank, then you can, with some certainty, use W/m2 to estimate PPF at specific water depths.
> 
> So, to summate by example: if you have two 30 W T8 tubes they are emitting approximately 60 PAR. If you have a good reflector that can focus all the light into the tank (which is impossible but lets just pretend) which is 36 x 12 inches in surface area you will get 222 PPF (PPF = PAR/(0.9 x 0.3 m)). Assuming 70% of the light actually enters the water, this will mean you will have about 99 PPF at 15 inches of _water _depth (not _tank _depth). More than enough for Glosso and HM and unless you have ample CO2 and nutrients you will get an algae soup. Without reflecors the value would be closer to 30-40 PPF which attests to the old adage that 2 full length tubes are enough to grow just about any plant.
> 
> 
> I'm having a hard time understanding this and it's relation to the chart. I have a 5.5 G tank with a 13w 6500k CFL about an inch from the surface in hood with no reflector. So I'm reading this noticing I'm losing a ton of light due to it being parallel to the surface and without a reflector but unless I'm reading the chart wrong since my bulb is probably 8 inches from my tanks lowest point my par is extremely high. I'm just trying to figure out what my par is and what category it falls in. Judging by the coloration of my plants I always thought it was low to medium-low at best. Am I opp operating at 1 p/w? So I'd need a 30w cfl for my 5.5g tank. My betta would probably think he's in the interrogation room


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## Hoppy

Here is a good article explaining what "PAR" is, by Li-cor, who make the best PAR meter in the world, as far as I can find out. http://www.licor.com/env/applications/photosynthetically.html

All PAR measurements I have heard about or seen, use PAR to mean photon flux per square meter per second, which means it is a measure of the light intensity at a surface, not the light emitted by a source of light. I would welcome a link that says PAR is a measure of the light emitted by a source of light.

Here is another article that somewhat clears up the difference between "PAR" as a measure of what the light source produces and what the intensity of light at a surface is. http://openwetware.org/images/e/e8/Conversion_lux.pdf It seems that our "PAR" should always be called "PPFD" instead. But "PAR meters" don't measure the total emission of light from a source, but the PPFD at the surface being illuminated, a much, much more useful parameter. 

Curiously, note that, for a cool white fluorescent source, the factor to multiply lux by to get what we call PAR, is .013, or 1/77, remarkably close to the 1/78 that I found experimentally.


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## xfatdannx

There is SOOO much info here i am very happy for it. I am trying to get the right balance between light and Co2 now for a high light tank. I have a 20g Tall (aprox 24in from light to substrate). Currently running two t5ho bulbs one at 6500k and one at 5000k. Would you suggest a change to get to high light or would you say i am there? I seem to get algae blooms when running both lamps, not sure if this is too much light or inadequate Co2. Thanks for any help you can provide, you have already done so much Hoppy.


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## Shark_

This is awesome information. Now we need the plant database updated with PAR values required to grow each type of plant. Otherwise measure by PAR seems pretty useless.


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## Hoppy

xfatdannx said:


> There is SOOO much info here i am very happy for it. I am trying to get the right balance between light and Co2 now for a high light tank. I have a 20g Tall (aprox 24in from light to substrate). Currently running two t5ho bulbs one at 6500k and one at 5000k. Would you suggest a change to get to high light or would you say i am there? I seem to get algae blooms when running both lamps, not sure if this is too much light or inadequate Co2. Thanks for any help you can provide, you have already done so much Hoppy.


If you look at the chart in the first post in this thread, the PAR you get from a T5HO light depends on who the manufacturer is - actually on how good the ballast and reflectors are. The color temperature is not a consideration when looking at PAR. Color temperature does affect what the tank will look like when lighted with those bulbs. And, the spectrum of light produced by the bulbs affects how much of the PAR emitted by the bulb is readily usable by the specific plants you are growing. But, that is another subject.


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## Hoppy

Shark_ said:


> This is awesome information. Now we need the plant database updated with PAR values required to grow each type of plant. Otherwise measure by PAR seems pretty useless.


In the low tech forum there is a long thread with a listing of "low light" plants, but, unfortunately the definition of "low light" was a watts per gallon definition, making the list just barely more than useless. In the Aquatic Plant Central forum there is a great "plant finder" list, but it, too, lists the lighting needed for each plant in terms of watts per gallon, greatly reducing the usefulness of the list. It will be a long time before there is a similar list that includes the PAR needed to grow the plants well. Someone who is looking for a good project should take this on :biggrin:


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## xfatdannx

I didn't see mine on that chart, its a ZooMed dual t5ho and the reflector is mirror like...its bright!

so if it has that real nice reflector, are you in essence, shining two bulbs at once or do you lose some of the reflected light?


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## Seadon

Ok so I have 36" 4 bulb i sitting on the rim of my 29 gal. And I'm getting moderate algae growth, I plan on switching to a 2 lamp 30"coralife fixture this week, will this solve my problem or is co2 a must?


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## newbieplanter

Seadon said:


> Ok so I have 36" 4 bulb i sitting on the rim of my 29 gal. And I'm getting moderate algae growth, I plan on switching to a 2 lamp 30"coralife fixture this week, will this solve my problem or is co2 a must?
> 
> 
> Sent from my iPhone using Tapatalk


Instead of getting a 2 bulb fixture why not just turn 2 off or take em out of the fixture u got now? If u read this post u will see that all those things lights,co2,ferts along with plants have to be in sync an u should have low to no algae. The Man who wrote this will tell u what u need to get it under control, but i think its also writen in here whT type of light u have weather it be low,med, or high.


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## Seadon

The 4 bulb fixture is really for my 75 gallon tank that isn't complete at the moment, so I was using it as interim lighting until the fixture meant for this tank arrives, but if it doesn't come today taking 2 bulbs out would'nt be a bad idea. I'll have to comb through here a little more carefully I guess and see if I can't find what I'm missing


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## Seadon

Hi I have gone through the first few pages of info on here and I have 2 questions, 1 does anybody know if a 30" 2 bulb HO coralife fixture is enough to fully light a 29 gal 30x12.5x18H without many dark spots, meaning areas where plants won't grow.
2. Similar question but a 75 gal. 48x18x20H and a 36" 4 bulb HO aquaticlife fixture


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## Seadon

The coralife will be about 2 inches from the surface so 20-21" from substrate.

The aquaticlife about 4-6" from the surface so 26"+ from substrate.

Both fixtures are on the PAR chart on the first page, I'm just reading a few pages on where hoppy says it might be better to use 2 shorter fixtures side by side on an 18" wide, or maybe it's 4 small fixtures, 2 on each half of the tank, I need someone to clarify lol. 


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## greenmerc

Hello there! Very nice thread! Im gonna be working on a planted tank in April. Was wondering what type of light I would need for a 80"x24"x18" tank, im planning to go low tech w/o co2 and growing low-med light plants. I think whats available here in my area is quite limited to all purpose bulbs for the home, no special ones like LEDs, metal halides and so forth. Ive seen CFLs and T8s. Any suggestions in terms on what PAR rating i should be looking into?


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## Seadon

greenmerc said:


> Hello there! Very nice thread! Im gonna be working on a planted tank in April. Was wondering what type of light I would need for a 80"x24"x18" tank, im planning to go low tech w/o co2 and growing low-med light plants. I think whats available here in my area is quite limited to all purpose bulbs for the home, no special ones like LEDs, metal halides and so forth. Ive seen CFLs and T8s. Any suggestions in terms on what PAR rating i should be looking into?



The 1st through 3rd or 4th page will help you out immensely if you are thinking about HOT5 lighting...especially the part where hoppy talks about fixture spacing for tanks 18" across and more. I believe someone w/ a similarly sized tank asked a similar question, I.e. A 72"x?x? Tank...I would definitely suggest a sticky for this thread if you are looking for the right lighting, it has saved me a ton of trial and error, that's for damn sure!


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## JPrice904

bigred87 said:


> Waaaait!! so Hoppy if i place a Home Depot 2 bulb Diamond Plate Shop Light on top of my 60 gallon ( 24in from the gravel) I am going to have Medium light???


I have a similar question. I have the standard tank lights set up on my standard 55G. I have fake plants right now but looking to get into a low light setup. I have a sand substrate so I will supplement with tabs.

I was considering getting the diamond plated shop light from HomeDepot but now I'm concerned that will give me too much light and I just wonder if I should stick to my 2 15w T8 bulb setup (one per ballast). I would rather not get into CO2 but I would like to achieve moderate growth. 

My question would be before I purchase this shop light should I stick with the 15w x2 (30w) setup or spring for the shoplight? I think from looking at your chart, my current setup, would give me 20-30 PAR which would achieve a low light setup. That's looking at the black line defined as "one bulb with typical white inside".


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## Seadon

JPrice904 said:


> I have a similar question. I have the standard tank lights set up on my standard 55G. I have fake plants right now but looking to get into a low light setup. I have a sand substrate so I will supplement with tabs.
> 
> I was considering getting the diamond plated shop light from HomeDepot but now I'm concerned that will give me too much light and I just wonder if I should stick to my 2 15w T8 bulb setup (one per ballast). I would rather not get into CO2 but I would like to achieve moderate growth.
> 
> My question would be before I purchase this shop light should I stick with the 15w x2 (30w) setup or spring for the shoplight? I think from looking at your chart, my current setup, would give me 20-30 PAR which would achieve a low light setup. That's looking at the black line defined as "one bulb with typical white inside".



If I was you I would go for the 2 bulb T5 HO from the Depot, or get a four NO T5 bulb fixture, and you will be in the more useful part of low light...I would also supplement substrate with Osmecote Plus, it is cheaper and much easier to get your whole substrate covered. Search it online it's not hard to find.


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## audioaficionado

Maybe go with a coarse sand or fine gravel substrate. You want to avoid too fine a substrate. Osmecote Plus will eventually end up on the substrate surface as little resin balls. You can ignore them or try to hide them in with the gravel/plants.


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## Absntmind

JPrice904 said:


> I have a similar question. I have the standard tank lights set up on my standard 55G. I have fake plants right now but looking to get into a low light setup. I have a sand substrate so I will supplement with tabs.
> 
> I was considering getting the diamond plated shop light from HomeDepot but now I'm concerned that will give me too much light and I just wonder if I should stick to my 2 15w T8 bulb setup (one per ballast). I would rather not get into CO2 but I would like to achieve moderate growth.
> 
> My question would be before I purchase this shop light should I stick with the 15w x2 (30w) setup or spring for the shoplight? I think from looking at your chart, my current setup, would give me 20-30 PAR which would achieve a low light setup. That's looking at the black line defined as "one bulb with typical white inside".


I use the diamond plate shoplight over my 55g and it works great. I suspended it 6""-8" above the tank, but you could rest it on top using window screen and it would work well.

Anywhere from a single T12 resting on top of the tank to 2 T8's would be optimal for low light-medium light depending on the reflectors.

Don't bother with T5HO unless you are considering a one bulb fixture as that would be to much light for low tech and you will definitely have algae problems down the line. If choosing T5NO then go with a single bulb resting on top or 2 bulb suspended.


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## Seadon

Absntmind said:


> I use the diamond plate shoplight over my 55g and it works great. I suspended it 6""-8" above the tank, but you could rest it on top using window screen and it would work well.
> 
> Anywhere from a single T12 resting on top of the tank to 2 T8's would be optimal for low light-medium light depending on the reflectors.
> 
> Don't bother with T5HO unless you are considering a one bulb fixture as that would be to much light for low tech and you will definitely have algae problems down the line. If choosing T5NO then go with a single bulb resting on top or 2 bulb suspended.



To me, IMO, that's a little under kill, with a single T12 or dual t8's even it would be pretty slow growth on 99% of plants in a 55gallon, and the growth you got would be tall lanky 'reaching' for light. And I have a 2 bulb t5 NO fixture on my 29gallon and it wouldn't grow even the least demanding of plants, like water sprite, and wisteria, onion bulbs etc. worth beans...even a single T5 HO would have to have a pretty amazing reflector to provide proper coverage front to back, side to side, like a $200-$300 ATI or something. A single T5 NO WILL NOT grow anything, and the tank will be dim and disappointing...trust me I have experimented with everything listed above except the single T5's...dual T8's single T12 dual T5's NO & HO the only thing on here I can recommend to you would be dual T5 HO suspended to reduce PAR.


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## Absntmind

My suggestions are based on personal experiences along with others I know. My last light was a dual T5NO sitting on top and it was to much light. Plants grew great but so did algae. I switched to dual T8s based on advice I should have taken years ago. Regarding a single T5HO, that has higher output than single T8.I know people who have grown very lush low light tanks with such. While it took longer to grow they also didn't have the algae problems I did. To each his own, yet IMHO dual T5HO is to high for a low light tank.


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## Beelzebubbles

Im using the aquaticlife dual t5HO on my 29 gallon, soon to be high tech planted tank.

would linking another one of these fixtures be overkill?


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## Yiannis

This is the balb that I just installed in my rank...no re reflector...horizontally placed....how much pars will ot register? Its 12 inches from the substrate


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## newbieplanter

Yiannis said:


> This is the balb that I just installed in my rank...no re reflector...horizontally placed....how much pars will ot register? Its 12 inches from the substrate


People will need the size of ya tank to tell.


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## Yiannis

20 litres planted with hemianthous Cuba...I dont think tank size has anything to do with pars reached to the substrate...light os 12 inches from subsrate...

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## newbieplanter

Yiannis said:


> 20 litres planted with hemianthous Cuba...I dont think tank size has anything to do with pars reached to the substrate...light os 12 inches from subsrate...
> 
> Sent from my GT-I9505 using Tapatalk


Well if u have that bulb an u tryin to light the whole tank different story. The par directly below bulb will be higher than par to front, back, an side to side.


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## eisBear

*29gal 18" high*

I'm super glad that there is a PC chart there (Thanks Hoppy), it seems like info available on them is becoming a bit scant. I suppose the tech is just getting old or something. I'm trying to get the lights right on my 29gal which is 30w x 12d X 18h.

I have a dual bulb 65W power compact fixture and I'm only using one bulb, a 6500K 65W coralife 22" bulb that's new. I bought the fixture second hand and it is a 'current usa' brand that seems to have an OK reflector. Based on the PC chart, when its sitting about 2.25 inches above the tank, (about 18 inches above the substrate), I should have around 40 PAR. 

I keep getting algae and the light seems bright at that height so I just got finished raising it to about 25 inches above the substrate. My tank could probably be called 'moderately' planted. 

In this case, it looks like I might have just under 30 PAR. Did I go up too high? Would I have that much more PAR just because the light is 65W, instead of the tested 55W? It would seem that being in the meaty part of 'medium' would not cause fast algae bloom. I'm trying to have it low-medium light (I do have co2) to avoid algae and keep my shade-loving Tetras and Rasboras happy, plus also avoid what my wife and I were calling the 'x-ray' effect of the bright light on the fish. 

Are all of my plants going to die off at the bottom part of the stem or does this sound like a good range of height to start from for a low-medium light tank?

I guess I don't want to be way-overestimating the power of the single lamp only to learn that I needed to look elsewhere to solve my algae problem after all of the bottom plants start suffering. In my house, with my water anyway, so far, the lower the light, the less algae no matter the set-up (so far), so I'm kind of going off of that.


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## Hoppy

The only 65 watt PC lights I have seen had very poor reflectors, so they would give you about half the PAR that the 55 watt AH Supply lights give. But, I am sure I haven't seen anywhere near all of the 65 watt PC lights that are available.


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## burr740

I would look at ferts to see if you have a limiting factor somewhere that is keeping your plants from fully utilizing the current level of light, which honestly doesnt sound like too much. The general consensus seems to be to give plants everything they need to grow and algae wont be much of an issue. In my limited experience that has proven to be the case.

Also would like to take this opportunity to thank you, Hoppy, both for your work in this thread and so many others regarding lights. You have helped me understand so much!


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## eisBear

OK, thanks for the responses all!



Hoppy said:


> The only 65 watt PC lights I have seen had very poor reflectors, so they would give you about half the PAR that the 55 watt AH Supply lights give. But, I am sure I haven't seen anywhere near all of the 65 watt PC lights that are available.


 So at 25 inches maybe more like 15-20? That's low eh? Yall might be right I may need to rethink the 25 inch height in that case. Here is what the reflector looks like, it doesnt form around the bulbs like the AH but it does have a fairly mirror like finish and wraps around the outside of the bulbs. Dunno if that helps. Thanks again!


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## plantbrain

Hoppy, 

I have a new Apogee light meter now. It's pretty well corrected for the T5's for PAR and the curve. Has a few more options. Has other corrective %'s for other bulb types. 

FYI.........


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## mistuhmarc

Hey Hoppy,

I'm planning on updating the light fixture on my parent's 30gallon tank to three clamp light CFL fixtures. Each fixture will have a 23w CFL in I think more than likely 8.5" diameter domes. Would this be sufficient as medium light for the tank? Thanks!


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## rthomas529

How can a 26w cfl produce 50% of par as a 23w cfl?


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## Hoppy

plantbrain said:


> Hoppy,
> 
> I have a new Apogee light meter now. It's pretty well corrected for the T5's for PAR and the curve. Has a few more options. Has other corrective %'s for other bulb types.
> 
> FYI.........


Sorry, I haven't been monitoring this much, and I'm in the middle of moving to an apartment, so my aquarium activities are turned off for now. Once I get moved and settled in a bit, I will want to borrow that PAR meter for awhile. I will let you know.


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## sprocketdiver

Hi. I'm concerned I don't know what I'm dealing with. I have a 15 gallon. It's taller than wide. I have my light suspended from the ceiling. Not sure what distance to hang it though. Measured from the substrate. It's a 4 bulb t5ho fixture. But the reflector is funny. Advice. The reflector has loads of dimples all over it. It's not smooth.


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## Hoppy

sprocketdiver said:


> Hi. I'm concerned I don't know what I'm dealing with. I have a 15 gallon. It's taller than wide. I have my light suspended from the ceiling. Not sure what distance to hang it though. Measured from the substrate. It's a 4 bulb t5ho fixture. But the reflector is funny. Advice. The reflector has loads of dimples all over it. It's not smooth.


A 4 bulb T5HO light is very likely to need to a considerable distance above the substrate, or you will have much more light than you can easily live with. I would use just two bulbs at a time, and try it at about 24 inches from the substrate. That should give you something in the low to medium light range.


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## sprocketdiver

Thanks for the reply, some photos of the set up, I'm having trouble with algae and my plants not really taking off, 
It's economic complete substrate and 1-2 bubbles co2 a second into an inline diffuser reactor
Baby tears all but dead now, watercress is spindly and very unhealthy, only the Brahmi is doing ok,


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## sprocketdiver

Ok try again so lights set for 7 hours continuous now 3 catfish and new plants.


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## IiScaPeJuNkiEiI

About the par data for cfl lights in a dome fixture.. Is the measurement taken with a polished dome? Or a regular satin finished one? Need to know how the par is affected either way please. Thanks!


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## drasan

I appreciate all of your research & explanations - However, i have no clue what it all means. I asked my son who is currently in college & he had no idea either. Is there a simple way for a person of normal intelligence to figure out if 2 T8 aqueon 15 watt 18" bulbs are enough for a low light planted 55 gallon tank. The lights are in the original hood. Please help, I'm 53 and don't feel like going back to school. LOL Thanks


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## jeffkrol

drasan said:


> I appreciate all of your research & explanations - However, i have no clue what it all means. I asked my son who is currently in college & he had no idea either. Is there a simple way for a person of normal intelligence to figure out if 2 T8 aqueon 15 watt 18" bulbs are enough for a low light planted 55 gallon tank. The lights are in the original hood. Please help, I'm 53 and don't feel like going back to school. LOL Thanks


sure.. you have 30W of T8's over 55gal.. Even w/out a PAR meter I can guarantee low light...


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## drasan

Thanks for the help.


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## candymancan

I still don't think this PAR is correct... If this were true then having 1 T8 light or a Power compact light in a 25 inch tall tank apparently doesn't matter they both are low light... lol AIn fact this graph shows a PC light is almost identical to a single T8 light and that deff cant be true.. I've held a T8 6700 and a PC 6700 together and the PC is nearly double the brightness in the tank height tank. In fact I had 2 T8's and 2 T5NO over my 27g hexagon and replaced those 4 lights with 1 Power compact and my plants are still red and purple..

This is a Joke because I have some pretty strong reds and purples in some of my medium/high light plants using my Power Compact lighting.. And whats is AHS PC ?? What does the AHS stand for ?

This graph is basically saying the par from 1 T5HO is almost 50 at 25 inches and a PC light is like 2 or 3 par at 25 inches.. HAHAH ok lol... Has anyone actually measured a PC light with a reflector... these NO REFLECTOR graph are very biased... Why are you comparing individual T5HO reflectors with T8's and T5NO or PC light with no reflectors or white back grounds..

I haven't seen a T5NO use a white background.. The ones I've seen use reflectors, and my PC lights have reflectors on them... what company sells a PC light with no reflector. I've searched google for HOURS i cant find one person who has done measurments on PC lights with reflectors.. So until then that graph you posted above.. lol..


PAR is another FAD like watts per gallon.. It isn't accurate when measured in the proper 400-700nm range. PAR only measures the ACTIVE radiation output of a light... Not the usefull radiation PUR... That can be used.. so this is exactly another WPG fad that i wish would just go away.... You can have 2 6700k bulbs and 2 Plant grow bulbs.. those plant grows will outgrow those 6700k yet how can that be if the PAR is the same ? Because PAR isn't measuring the usefull lighting.. omg.. this is giving me a headache


Also your chart you post Jeffkrol and the ones posted on this sticky.. The measurements are WAYYYY off.. The ones he posted for T5HO's using like 15 different fixtures.. the average PAR at 25 inches for TWO bulbs is around 40-56 PAR And his chart for the PC lights.. using 1 36 or 55w BULB for 25 inches the par is 23.. So using a duel fixture for 2 bulbs the par is around 46. That's about the same as most of the T5HO light fixtures soo according to these charts a PC light near identical to a T5HO.. just depends on the reflector your T5HO has... Yet according to your chart PC bulbs are almost like T8's...


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## jeffkrol

candymancan said:


> I still don't think this PAR is correct... If this were true then having 1 T8 light or a Power compact light in a 25 inch tall tank apparently doesn't matter they both are low light... lol AIn fact this graph shows a PC light is almost identical to a single T8 light and that deff cant be true.. I've held a T8 6700 and a PC 6700 together and the PC is nearly double the brightness in the tank height tank. In fact I had 2 T8's and 2 T5NO over my 27g hexagon and replaced those 4 lights with 1 Power compact and my plants are still red and purple..
> 
> This is a Joke because I have some pretty strong reds and purples in some of my medium/high light plants using my Power Compact lighting.. And whats is AHS PC ?? What does the AHS stand for ?
> 
> This graph is basically saying the par from 1 T5HO is almost 50 at 25 inches and a PC light is like 2 or 3 par at 25 inches.. HAHAH ok lol... Has anyone actually measured a PC light with a reflector... these NO REFLECTOR graph are very biased... Why are you comparing individual T5HO reflectors with T8's and T5NO or PC light with no reflectors or white back grounds..
> 
> I haven't seen a T5NO use a white background.. The ones I've seen use reflectors, and my PC lights have reflectors on them... what company sells a PC light with no reflector. I've searched google for HOURS i cant find one person who has done measurments on PC lights with reflectors.. So until then that graph you posted above.. lol..
> 
> 
> PAR is another FAD like watts per gallon.. It isn't accurate when measured in the proper 400-700nm range. PAR only measures the ACTIVE radiation output of a light... Not the usefull radiation PUR... That can be used.. so this is exactly another WPG fad that i wish would just go away.... You can have 2 6700k bulbs and 2 Plant grow bulbs.. those plant grows will outgrow those 6700k yet how can that be if the PAR is the same ? Because PAR isn't measuring the usefull lighting.. omg.. this is giving me a headache
> 
> 
> Also your chart you post Jeffkrol and the ones posted on this sticky.. The measurements are WAYYYY off.. The ones he posted for T5HO's using like 15 different fixtures.. the average PAR at 25 inches for TWO bulbs is around 40-56 PAR And his chart for the PC lights.. using 1 36 or 55w BULB for 25 inches the par is 23.. So using a duel fixture for 2 bulbs the par is around 46. That's about the same as most of the T5HO light fixtures soo according to these charts a PC light near identical to a T5HO.. just depends on the reflector your T5HO has... Yet according to your chart PC bulbs are almost like T8's...


AHS is AH supply:
http://ahsupply.com/

As to 1) PAR meter accuracy.. I've stated and shown numerous times the "inaccuracies" of most meters..w/ the exception of a Li-Cor
2) Yes PAR measures (assume a li-cor for now) all light from about 400-700nm and treats each equally, which is not "exactly" correct based on the PUR idea...but it is relatively close..

IN general think of a progression from worse to better..
visual is worse than watts which lumens which is worse than lux which is worse than PAR which is worse than PUR which is worse than ind. measurements per species based on spectrum and quantum efficiency of a light......

any "economic" PAR meter has a terrible bias against light in the 660nm range and will under-sample it. It will also over-sample green and ect. each band having a corresponding inaccuracy..The 'hope" is w/ a full spectrum light that it averages out........  An "assumption"...........

Obviously "precision and accuracy are not at a "research" level.. and errors occur..
None should be taken as "scripture"... 










Red line is approx how a Li-Cor measures light.....









As a side note T8's are marginally less efficient than a T5.. As to PC.. ??? 


> a. T8 is 40% more efficient than T12.
> 
> b. T5 is 51% more efficient than T12.
> 
> Yet, T5 in this environment is only 9% more efficient than T8.


without measureing each ind. light in it's "real world" env. all you can do is make assumptions..

I hear what you are saying in the fact that one shouldn't rely on any one measurement.. but one needs a starting point......

Even PUR is inaccurate based on an individual plant species..Since that "green line" is actually taken from an "average plant" response.. meaning an overall based on who knows what species..
speaking of PUR apparently there is one even better.......


> PSR, can be defined as the amount of radiant energy that can be
> converted into and stored as chemical energy, in the form of organic matter created through
> photosynthesis. There exists an obvious relationship among these three quantities:
> PSR < PUR <
> PAR
> Comparison of the extreme terms, PSR and PAR, leads to the concept of efficiency of utilization
> of radiant energy entering the water, by the microalgae


http://www.biophotix.com/resources/Par+vs+PUR+vs+PSR-+20130214.pdf

good luck finding a PSR (or PUR) meter.. or a cheap way to measure it.......


> PAR has been defined as the amount of radiant energy, preferably expressed as quantum units, available
> within the approximate
> spectral range from 350 nm to 700 nm (Tyler, 1966).
> This definition does not prejudge the usefulness of this energy for microalgae because all photons,
> regardless of wavelength, must be counted. In order to be efficient in the photosynthetic process, these
> photons must be absorbed by the algal pigments. Thus one can define the photosynthetically usable
> radiation (PUR), as the fraction of such wavelength that it can be absorbed by the algae. PUR depends
> upon the pigment composition of the algal population as well as on the spectral composition of the
> submarine radiant energy.
> Lastly, only a fraction of the absorbed energy is really used in the photosynthetic process. The
> transformation of absorbed energy into chemical energy is carried out with variable yields. A quantum
> yield, Φ, has been defined by plant physiologists as the number of CO2
> molecules transformed (i.e., reduced to carbohydrate), per quantum absorbed, or the number of CO2
> moles per Einstein absorbed


http://www.obs-vlfr.fr/LOV/OMT/fichiers_PDF/Morel_DSR_78.pdf
Do we really need to go to that level??


----------



## candymancan

Yes but the graph you showed im assuming you didn't make that one, still seems very biased towards PC lighting...

I guess it makes sense if you have no reflector lol but come on even the basic PC fixtures have metal reflectors. The one I have from Current its a duel 65w one. If you go back to page 22 a guy posted pics of his.. That's the one I have.. It doesn't have curved metal for each bulb so I can see how each bulb would wash the other out.. but its still a reflector and the sides are curved at least. I have thought about taking the reflector out myself and bending it in the middle to better reflect the light. I like those reflectors on that website you linked though.

But yea even with a crappy reflector or no reflector a PC light surely is better then any T8 light lol.. As an example I took an old T8 fixture you know those bulky ones with the white reflectors.. I gutted it of the the t8 stuff and I put a 65w PC ballast inside and I mounted the light directly inside the white reflector the t8 bulb used to sit in lol.. but 1 65w PC bulb is deff a lot stronger lighting then an 18W T8 lol. Its also better then my duel T5NO with a metal reflector .. My plants.. some of which are high light plants like Tiger Lotus and Red Combamba and red ludwigia and one I can never get the name right.. Lippphidurious or whatever its called lol.. They are all red/purple...

Ever since I replaced the duel T5NO's and that T8 (I had 4 lights over this tanks 2xt8 plant grow and the duel T5NO) with just this one PC light (6700/10k combo) my Red Ludwigia instead of being green with those 4 lights is now red.. and my Lipphidious plants instead of being only purple half way up the tank are now purple all the way near the bottom about 20 inches down (its a 27g hex about 25 inches tall)

So from my personal experience this single PC light using a white T8 lights reflector (heck 4 inches of the light isn't even in the reflector) is better then the 4 combined T8/T5NO lights I had. This pic is my ghetto PC in a T8 hood.. see the ends.. they aren't even in the reflector.. Plus the 10k on this light isn't exactly ideal for color spectrum... And yet look at my plants.. Since they are about 5-6 inches tall right now (I trimmed them).. According to your chart with my tank being 25 inches tall and my lights another 2-3 inches above that... subtract 6 inches.. my PAR should be like only 10 or so. Yet why are my medium/high light plants red ? I don't use CO2 either..


Sooo yea again like I said PAR is overrated... big time. That and your chart you linked is way off lol.. The one on this thread is more accurate if you go by PAR his chart with my 25 inch tall tank, lights 3 inches above minus the 6 inch growth of my plant my PAR with the PC light is about 34-40 which is around the medium light according to your chart and what he said.. Because if I went by your chart my PAR being at 10 trust me my plants in the pics would be green.. I have had them in really low light tanks and they just grow green.. But according to your char my part is really low light and yet they are very colorful .


----------



## Hoppy

Candymancan, how would you advise someone on what specific light fixture to use on a specific tank, in order to get a a medium light intensity at the substrate in the middle of the tank? If you have an idea about how to do it with better accuracy, please post your idea here. However we do it today, in a few years it is likely that someone will find a better way to do it.


----------



## jeffkrol

Besides some spectral differences.. PC's are not more efficient than t5's.. 


> Well after further analyzing the data on the sites
> 55w PC 21" = 79 lumens per watt = 4,345 lumens
> 54W T5 HO 46" = 93 lumens per watt = 5,022 lumens
> 65w PC 21" = 79 lumens per watt = 5,135 lumens


http://www.thereeftank.com/forums/f6/t5-vs-power-compacts-98427.html

4 (3.6) 18" t5's "should" give the same results as your pc..given the same spectrum..









http://current-usa.com/lighting/sunpaq-lamps/

http://current-usa.com/files/CURR05020_SunPaqTrifold_v3.pdf

Current states almost 100l/w.. I "assume" from their numberless chart.. 










BTW: their spectral charts make no sense.. showing heavy output from 300-400nm (you have to zoom in on the pdf).. BUT if real, it would explain low PAR numbers since light below 400nm is under-sampled..


----------



## candymancan

a PC is way more efficient then a T5NO or a HO.. Im saying I had 2xT8 Floramax bulbs, and 2x T5 Normal Outputs 1 a plantgrow and 1 a daylight bulb I had 4 lights on the tank and this single PC is growing my plants better and 1 of the tubes is a 10k tube which isn't exactly ideal for plants. Yet according to your chart you linked my single PC shouldn't be able to grow my red plants like it is

Im not saying I have some great theory that's better then PAR all im saying is people rely too much on this stuff. Im by far no expert in lighting.. But based on my own experiences using PC lighting its a lot better then a T8 or T5 NO.. And similar length T5HO's its better

Also Per watt/ length of the bulbs PC is more efficient then a T5HO.. a 65W PC bulb is only like 22 inches long You cant compare a 65w PC bulb to a 54 watt T5HO because honestly... who is going to use a 22 inch PC over a 48 inch long 55G tank ???? I have the 65 watt ones over my pentagon that's 30 inches long and it barely lights the corners of the tank ... A similar wattage T5HO is what near 55 watts but it is like 48 inches. double the length. If you want to compare a T5HO to a PC light at least compare the bulbs of the same sizes, so if you want to go on a 55g tank a 48 inch PC light is going to be 96 watts.. Im pretty sure that bulb will have more Lumens then a T5HO.. Nearly double more lumens actually.. and most PC fixtures are duel fixtures.. That's nearly 200 watts... a duel T5HO will be what 110 watts ? What would the lumen output be for 2 T5HO's ? Around 10k ? And those 2 PC's would be what ? I b elieve the 96 watt bulbs are 84 Lumens per watt.. That's 8064x2 is 16128 lumens... 

So you got a 55G tank.. One with 10k Lumen 2X T5HO and one 55g with 16k lumen duel PC... Honestly which would you chose ? Also the PC has better light choices.. being 2 bulbs in 1 you could get one as a 6700/10k combo and the other a plant grow combo and with that plantgrow combo it will be even better then the T5HO's... The T5's are stuck with 2 bulbs.. so you can have what a 6700k and a plantgrow ? Or a 6700/10k or what not.. Essentually with the PC you have 4 different bulb combo's and the T5's are stuck with 2.

Do you guys get what im getting at here ? And im talking with comparable reflector's.. The only problem with PC is they are hard to come by except for online... Heck even T5 bulbs are starting to disapear


----------



## jeffkrol

candymancan said:


> a PC is way more efficient then a T5NO or a HO..


not by any real world measurements.. T5's LED and PC's all better ones approach or slightly exceed 100l/w..........LED becoming the de-facto king of L/W...
47W GE is 4800 initial lumens w/ 4410 mean.. 93.8 L/W........ about the same as the PC...

Density per inch is another story.. Your PC is 44" effectively.. 3.6x 18" = 64"...

4-18" T5's 2 @10000k [email protected] 6500k assuming equal phosphors to get those CCT's..is actually better than your PC............


----------



## candymancan

Im going by the size of the tubes.. That was the main advertisement with PC's when they were introduced they were more efficient then T5's in respect to there size. No one puts a 65w 22 inch PC on a 55-75g tank.. So to compare sizes you need go to the equal length PC and that would be the 96 watt one. Its double the wattage of a T5HO that's 48 inches... sure that's obvious... but its lumen output is nearly double as well. A 21 inch T5HO is only 24 watts.. Going by the lumens of the bulb... which range from 85 up and down.. But lets go by you 93. That's only 2200 lumens.. The PC puts out 5,100kaccording to your chart. That's almost triple the lumen output.


----------



## jeffkrol

candymancan said:


> Im going by the size of the tubes.. That was the main advertisement with PC's when they were introduced they were more efficient then T5's in respect to there size. No one puts a 65w 22 inch PC on a 55-75g tank.. So to compare sizes you need go to the equal length PC and that would be the 96 watt one. Its double the wattage of a T5HO that's 48 inches... sure that's obvious... but its lumen output is nearly double as well. A 21 inch T5HO is only 24 watts.. Going by the lumens of the bulb... which range from 85 up and down.. But lets go by you 93. That's only 2200 lumens.. The PC puts out 5,100kaccording to your chart. That's almost triple the lumen output.


I agreed w/ you that inch for inch the PC had a higher power density. I disagree that w for w it is more efficient.. Numbers prove that..
On a side note.. you can (both real world and theoretically) overdrive 2 18" t5's to equal a 65w PC.. Does that translate to equal lumens..???? Probably not.


> 48" 54w bulbs are driven to 85 watts. I think 36" bulbs 54 watts, 24" bulbs to 39 watts, but not as certain on the smaller bulbs


http://www.reefsanctuary.com/forums/diy/51607-how-do-you-overdrive-t5-bulb.html
Point is the PC's ARE specially designed compact flourescents that can handle high power loads in a smaller package natively... but again w/w they are no better than "good" t5's.. only smaller...
The TERM efficient in this case has more than one way to look at it.......

As a summary of my "thinking" .. Yes some PC could definitely be underestimated as to PAR, PC's have a high density per inch, watt efficiency is equal to most other good flourescents, and falling behind LED's (for fun) AND as a food for thought (and seeing that spectral chart) my personal belief that high "near UV" will help "color" red plants..something a bit lacking in LED's or lower output/different spectrum bulbs (again for fun)...


----------



## Hoppy

One way T5HO bulbs have an edge over PC bulbs is that you can design a reflector that greatly increases the light that reaches the aquarium substrate because it is a linear bulb. But, a PC bulb, being a bulb consisting of two very closely spaced tubes, doesn't allow for an equally effective reflector. A lot of the light emitted by a PC bulb can't be directed down into an aquarium.

A 55 watt PC bulb can be compared to a 54 watt T5HO bulb - equal wattage, and the tube length is about the same also. But it takes two of the PC bulbs to light a 48 inch long tank, and only one T5HO bulb. Even if both give the same PAR reading at the substrate, it takes twice the wattage of PC bulbs to get that PAR. I believe the T5HO bulb, with a good reflector gives more PAR than the two PC bulbs with a good reflector.


----------



## candymancan

Hoppy said:


> One way T5HO bulbs have an edge over PC bulbs is that you can design a reflector that greatly increases the light that reaches the aquarium substrate because it is a linear bulb. But, a PC bulb, being a bulb consisting of two very closely spaced tubes, doesn't allow for an equally effective reflector. A lot of the light emitted by a PC bulb can't be directed down into an aquarium.
> 
> A 55 watt PC bulb can be compared to a 54 watt T5HO bulb - equal wattage, and the tube length is about the same also. But it takes two of the PC bulbs to light a 48 inch long tank, and only one T5HO bulb. Even if both give the same PAR reading at the substrate, it takes twice the wattage of PC bulbs to get that PAR. I believe the T5HO bulb, with a good reflector gives more PAR than the two PC bulbs with a good reflector.




A 54 watt T5HO is a 48 inch tube the 55w PC is around 20 inches.. Youre right it would take 2 PC lined up horizontally to light a 55g.. but why would you do that when you can get a 96w 48 inch PC and have greater light then a single 54w T5HO or 2 lined up 55-65w PC bulbs lol ?? You guys aren't making any sense here.

I really wish someone would measure the Par of PC bulbs... 36w-55-65-96w


----------



## roadmaster

candymancan said:


> A 54 watt T5HO is a 48 inch tube the 55w PC is around 20 inches.. Youre right it would take 2 PC lined up horizontally to light a 55g.. but why would you do that when you can get a 96w 48 inch PC and have greater light then a single 54w T5HO or 2 lined up 55-65w PC bulbs lol ?? You guys aren't making any sense here.
> 
> I really wish someone would measure the Par of PC bulbs... 36w-55-65-96w


 
I used the bulbs you mentioned both over my 55 gal and also my 80 gallon for a couple year's.
65 watt Straight pin PC bulbs mounted end to end in 48 inch fixture
bulbs are 22 inches long.
Also used 55 watt PC bulbs also 22 inches in same 48 inch fixture.
Was a bit much for low tech,NON CO2 and window screen was used to partially decrease intensity.
Didn't /couldn't use more light for low tech on my tanks.
I used the 48 inch PC fixture with mirror type reflector for it was layin around from salt water tanks that I used to dabble in ,and so no added expense for new fixture to grow weeds.
Earlier in this thread you say PAR is relied on too much,Is a fad, but yet you want someone to measure the PAR for PC bulbs you mention.?LOL
Title of this thread "Lighting a tank with PAR as opposed to watt's" is for now,, all most need to know when trying to discern what lighting might place one in high,medium,low light regions and thereby suggest where CO2 or lack thereof may be elephant in the room with respect to healthy plant growth.


----------



## candymancan

It is a fad but people constantly bash PC lights yet no one cares to measure them if you rely on PAR so much wouldn't it be fair to properly measure PC's and not just T5 lights


----------



## roadmaster

candymancan said:


> It is a fad but people constantly bash PC lights yet no one cares to measure them if you rely on PAR so much wouldn't it be fair to properly measure PC's and not just T5 lights


 
Only if your using power compact bulbs.
Mostly reef folks still using these bulbs which I actually quite like.
Anyone who believes PAR is a fad,is doomed from the outset in their effort's at growing healthy plant's.
More likely to experience spectacular algae growth with too much PAR and limited ability to supplement CO2 .
Hardly anynbody's effort's are thwarted by too little light/PAR.
The PAR values of a particular bulb or bulb's,are much more critical than color spectrum.
Most agree on this.


----------



## nonaldehye

no pun intended, I have seen the light--the watts/gal always struck me as utterly bogus---anyone who completed G12 physics knows energy intensity decreases by the inverse square of the distance--- and from this brilliant post, I can see I am growing algae b/c I have a PAR of 50 at the bottom on my 65G freshwater tank... and no co2...either hanging the lights and adding CO2.
Grateful!


----------



## mef1975

I have a Fish Focus Blue, 13K, 90 degree, from BuildMyLED, which specs indicate a PAR of 60, 24" under the water, 9" from center, where I happen to have a Red Tiger Lotus, so I take it that slowly increasing the CO2 (flourish excel) and ferts (nitrate, potassium, iron) will eventually make the green hair algae go away? How many hours a day should I keep the light on?

Also, am I to understand that one could use an incandescent bulb to dramatically increase the CRI and lux (visual brightness in the tank) without bringing up the PAR and PUR as drastically?

Finally, how does PAR and PUR differ? "Active, "usable", like what does that mean? Would PUR be more accurate when referring to photosynthesis? Why is that not used more than PAR? Or, is PUR like the PAR, but after it goes thru the water column, losing some, and not really applicable in manufacturing specs?


----------



## Hoppy

PAR is the light intensity in the 400-700 nm spectral range. PUR is the same thing except adjusted to give more weight to the intensity in the ranges of the spectrum that correspond to that which specific plants use, and less to that in the ranges of the spectrum that specific plants use much less of. You can directly measure PAR, but you have to calculate PUR. So, PUR for a specific light fixture is not readily available, nor easily obtainable. With a lot of effort it should be possible to make a light meter that actually reads in PUR, but I have never seen one, nor have I heard of the existence of one.


----------



## jeffkrol

Hoppy said:


> With a lot of effort it should be possible to make a light meter that actually reads in PUR, but I have never seen one, nor have I heard of the existence of one.


I believe PUR is also considered species specific.. so really not worth contemplating much at our "level"... I can think of more reasons not to stress it than reasons to...


----------



## RootedMind

What kind of PAR readings would you get with an 18w CFL and a 23w both in an 8.5 aluminum cone 18" from the substrate?

Only fools stop searching for knowledge.


----------



## mef1975

RootedMind said:


> What kind of PAR readings would you get with an 18w CFL and a 23w both in an 8.5 aluminum cone 18" from the substrate?
> 
> Only fools stop searching for knowledge.


Well, I'm pretty new at this, but from I can see in the charts at the beginning of this awesome thread, each light will likely give you something over 50 PAR, but under 100, although, that was a 10" cone, definitely appears to be enough light for CO2, right? Would the PARs be summed together? Maybe only if the lights are close together, would it surely be over 100 PAR?


----------



## RootedMind

That's what I was thinking, my lights are ~11" apart. Also, I believe I read that the smaller diameter of the cone the higher the concentration, so higher PAR

Only fools stop searching for knowledge.


----------



## RootedMind

I'm seeing 70 for the 15w and 115 for the 23w. My tank is 0.55m², so how would you figure it with 2 of each light in this order: 23, 18, 18, 23? At ~11" apart? 
I really wish I had a PAR meter

Only fools stop searching for knowledge.


----------



## RootedMind

I think maybe I should switch it to: 18, 23, 23, 18, BTW the 18's are 5500k and the 23's are 6500k, any thoughts?

Only fools stop searching for knowledge.


----------



## mef1975

RootedMind said:


> I think maybe I should switch it to: 18, 23, 23, 18, BTW the 18's are 5500k and the 23's are 6500k, any thoughts?
> 
> Only fools stop searching for knowledge.


Now, I could totally be wrong, but I think I read somewhere that the K range you ask about is representative of what daylight might be at the Earth's equator, which I guess would be a good thing when it comes to visual light and color rendering, but I don't really know, at all. That K thing confuses me a bit. I think the higher frequency ones have more of a bluish tint, and perhaps, can even penetrate deeper waters better, but as I said, I'm really not sure about all this, I too am an algae grower. lol


----------



## RootedMind

Lol, I understand the Kelvin part, really I'm just curious about my PAR readings. I appreciate you responding, though.

Only fools stop searching for knowledge.


----------



## CowBoYReX

@hoppy are you able to answer this?


----------



## Joost

Hi, 

A friend of mine is interested in using two CFL bulbs above his aquarium. The aquarium holds 54 litres (60 cm length x 30 cm width x 30 cm height). Two IKEA TERTIAL desk lamps will be used to mount the CFL bulbs in a vertical position. The TERTIAL desk lamps have a diameter of +- 16 cm (6,3 inches) and are painted white. The height, from substrate to light source will be approximately 44 cm (17 inches). Pressurized CO2 will be used (up aqua inline atomizer), therefore we're aiming for 35 to 60 micromols/m²/s at the substrate.

According to the chart, when the distance between the substrate and the light source is approximately 17 inches and a 15 watt CFL bulb is used, the CFL will provide about 75 micromols/m²/s at the substrate. Is this correct? This means that even 15 watt CFL bulbs provide too much light.

If the above is correct, should he be using 13 watt, or even less?

I look forward to your response!


----------



## burr740

Joost said:


> Hi,
> 
> A friend of mine is interested in using two CFL bulbs above his aquarium. The aquarium holds 54 litres (60 cm length x 30 cm width x 30 cm height). Two IKEA TERTIAL desk lamps will be used to mount the CFL bulbs in a vertical position. The TERTIAL desk lamps have a diameter of +- 16 cm (6,3 inches) and are painted white. The height, from substrate to light source will be approximately 44 cm (17 inches). Pressurized CO2 will be used (up aqua inline atomizer), therefore we're aiming for 35 to 60 micromols/m²/s at the substrate.
> 
> According to the chart, when the distance between the substrate and the light source is approximately 17 inches and a 15 watt CFL bulb is used, the CFL will provide about 75 micromols/m²/s at the substrate. Is this correct? This means that even 15 watt CFL bulbs provide too much light.
> 
> If the above is correct, should he be using 13 watt, or even less?
> 
> I look forward to your response!


Hoppy can correct me if Im wrong, but I believe the chart uses aluminum reflectors. A white reflector, while still good, is going to offer less than aluminum. How much less? Im not really sure. There is also the diameter to consider, 6.5" vs 10.5". 

Myself having used both 13, 18, and 23 watt bulbs in 8.5" aluminum domes, also ~17" from sub, with co2....I do not think 13 or 15 watt bulbs will be too much for you in those IKEA fixtures. I settled on 18 watts for the tank I mentioned, which is a standard 20H.


----------



## mrbigshot

if your talking a matte aluminium finish lish inside a clamp on shop light vs white paint (specifically matte finish than you would be incorrect). matte white paint would reflect more.


----------



## burr740

That's good info to have. Thanks. I believe the common clamp-ons would qualify as polished, not "highly polished" where it looks like a mirror, but more shiny than matte.


----------



## Joost

So anything ranging from 15 to 20 watts would be fine? I'm aiming towards 20 watt bulbs due to the succes of this person : http://www.plantedtank.net/forums/showthread.php?t=316009

He was using 23 watt bulbs in IKEA fixtures.


----------



## mcarroll

Excellent thread...as was the original....which I was just reading by chance of an unrelated Google search.

Hoppy posted:

http://www.plantedtank.net/forums/showthread.php?t=105774


> To compare this with "watts per gallon", I know that a couple of 2 bulb T12 fixtures will grow plants in a 55 gallon tank. That tank is 20 inches deep, so if the substrate thickness is about the same as the height of the bulbs above the top of the tank, each bulb should give about 9 micromols of PAR, or 36 micromols for 4 bulbs. That is right in the middle of the low light range. So my data is consistent with real life results.


Nostalgia! Facts haven't really changed though.

On to the reason for posting!


QUESTION FOR HOPPY:
Since decent lux meters are <$20 - within almost anyone's budget - is there a chance of seeing actual lux readings or the generation of some lux<>PAR conversion factors for the bulbs you take the time to look at?

I know they would be useful and appreciated! 

Thanks!

-Matt

P.S. Thought I'd seen more than one list of conversions "in the wild" before, but at present this 2008 Dana Riddle article is the only one I can find.


----------



## Raul-7

http://premiumaquatics.com/products/biotek-marine-btm3000-par-sensor-15-usb-cable.html

Here's a new PAR sensor that won't break the budget so to speak.


----------



## jeffkrol

Raul-7 said:


> http://premiumaquatics.com/products/biotek-marine-btm3000-par-sensor-15-usb-cable.html
> 
> Here's a new PAR sensor that won't break the budget so to speak.


Well it is an Apogee sensor.. w/ the same Apogee problem...










apogee is sure in no hurry to upgrade their sensor..


----------



## mcarroll

And 1300% more expensive than a lux meter. (Which is better than the usual recommendation at 2000% more expensive.) 

It's neat, but not priced for the crowd - which it really needs to be. (And is priced for the crowd, if we talk lux meters.)

Realistically, I don't see how many folks will ever justify spending more than around $15 on one. Most folks aren't that rich....even things like dosers, controllers and ATO's get skipped on a lot of tanks due to budget....and even I'll admit that those are far more useful than a light meter.

I think Apogee (and everyone else...the sensors are never perfect...look how the high end machines compensate for it) makes up for it in their calibration of the device. (Kinda like we would know a lux meter is off, but still find the results useful.)


-Matt

Bump: This gives about the best run-down of kinds of light meters that are used to measure illuminance. (All pretty much applies to PAR meters too.)

http://www.olino.org/us/articles/2009/12/07/measuring-illuminance-correctly


----------



## Hoppy

mcarroll said:


> And 1300% more expensive than a lux meter. (Which is better than the usual recommendation at 2000% more expensive.)
> 
> It's neat, but not priced for the crowd - which it really needs to be. (And is priced for the crowd, if we talk lux meters.)
> 
> Realistically, I don't see how many folks will ever justify spending more than around $15 on one. Most folks aren't that rich....even things like dosers, controllers and ATO's get skipped on a lot of tanks due to budget....and even I'll admit that those are far more useful than a light meter.
> 
> I think Apogee (and everyone else...the sensors are never perfect...look how the high end machines compensate for it) makes up for it in their calibration of the device. (Kinda like we would know a lux meter is off, but still find the results useful.)
> 
> 
> -Matt
> 
> Bump: This gives about the best run-down of kinds of light meters that are used to measure illuminance. (All pretty much applies to PAR meters too.)
> 
> http://www.olino.org/us/articles/2009/12/07/measuring-illuminance-correctly


Would you find $50 is too much to spend for a PAR meter with accuracy that approaches that of the Apogee PAR meter?


----------



## mcarroll

In the right ballpark - definitely the correct number of digits! 

...but still seems on the high side when I consider the effectiveness of the basic lux meter. Based on my experience so far, I'm just not sure it's >300% better to know the PAR number if you already have the lux.

I haven't seen a need for measuring below the water surface, in case waterproofing is a part of the cost. I'd suggest making that optional, if it's a factor, and offer one for less money that is simply (and only) converted to read PAR. I can see some wanting waterproofing, of course, since underwater measurements have been seen so many times in the forums...but it's definitely "extra".

If I didn't already have or know about the lux meter, I think $50 might be a decent price. Also if it was a fully supported product vs a (very good) DIY hack. I'd have to see, and ideally try it out, to say for sure. Lux meters are a well-known quantity and very inexpensive, so I have less hesitation there.

I don't mean to sound too critical....very cool project whose time has definitely come....just trying to be honest.

(For our purposes, I'm decidedly un-sold on the importance of knowing PAR...outside of comparing numbers to people who always report PAR. For others like D. Riddle, for example, who use PAR meters outside the hobby, I think I get it.)

.
.
.

And it'd still be really handy to have simple PAR<>lux conversions published for the lights you spend the time to check out.


----------



## Hoppy

The problem with using a lux meter to determine light intensity in PAR units is that lux meters read only the light in the green-yellow area of the spectrum, and entirely miss any light in the red or blue-violet areas. If you have a LED light, with 660 nm LEDs in it, plus some near IR LEDs, to give a more natural light spectrum, the intensity you measure with a lux meter will be way off, and there is no reliable conversion factor. But, if you stick with fluorescent lights you can easily make your own direct reading PAR meter:http://www.plantedtank.net/forums/showpost.php?p=5197961&postcount=47


----------



## mcarroll

You can see a link above I posted (#365) a list of existing PAR<>lux conversion factors....just hoping someone with both meters would feel inclined to expand on that work. Have to admit it was worth asking! 

Now back to successfully using a lux meter to set up lights in place of a PAR meter...


----------



## Trigger334

*My opinion*

Hello, I'm a member here, but don't post to often. I have been thinking about PUR a lot lately, because we have been getting a considerable amount of people asking questions about the topic. (I work for a online aquarium store). 

I made a video I thought covered the misconception of PUR, then discovered this thread when doing some more research about the topic.

Does anyone want to take a look at my video and see how they feel about PAR/PUR?

https://www.youtube.com/watch?v=-T4FKchXASs

Thanks for your thoughts! :icon_surp


----------



## mba

jeffkrol said:


> Well it is an Apogee sensor.. w/ the same Apogee problem...
> 
> 
> 
> 
> 
> 
> 
> 
> 
> 
> apogee is sure in no hurry to upgrade their sensor..



Jeff, 

Can you clarify what issue of the Apogee sensor you are referring to? A newbie like me does not understand the chart you provided with the closed caption. I'm planning to use the new Apogee sensor to measure my LED custom photon 48 planted version from reefbreeders (I believe you helped me build that led light fixture last year and some other users).


----------



## jeffkrol

mba said:


> Jeff,
> 
> Can you clarify what issue of the Apogee sensor you are referring to? A newbie like me does not understand the chart you provided with the closed caption. I'm planning to use the new Apogee sensor to measure my LED custom photon 48 planted version from reefbreeders (I believe you helped me build that led light fixture last year and some other users).


Well for a start, if the reefbreeders use any 660nm reds you will only measure, roughly 1/2 the PAR that it emits (depending on diode characteristics).. The Apogee has a sharp red measurement cutoff before "visible red" ends.
In deeper tanks, since some is "lost" anyways" this is not as important as in shallower tanks. 
somewhat also applies to low K whites 3500K or less.








you will also under sample blue wavelengths starting at 475nm and less (royal blue on down).

Lastly you will slightly over sample blue/greens to yellow/reds (orange) though this is minor.

Over all the error will not be critical.. but it would w/ measuring a light w/ 35% 660nm red and 66% high K white (6500K or better)

My "big dig" is I'm pretty sure apogee can "do better" if not to Li-Cor quality.. close to..
They use a cheap IR "cut" filter AFAICT which cuts too soon.
Apogee's inaccuracies are well noted w/ LED's and other "broken spectrum" lighting..they jut get a tad more crucial w/ LED.

you may only have, say, a 10-15% under-sample..

I would be the first to admit I'm a bit anal on this point.


----------



## mba

jeffkrol said:


> Well for a start, if the reefbreeders use any 660nm reds you will only measure, roughly 1/2 the PAR that it emits (depending on diode characteristics).. The Apogee has a sharp red measurement cutoff before "visible red" ends.
> In deeper tanks, since some is "lost" anyways" this is not as important as in shallower tanks.
> somewhat also applies to low K whites 3500K or less.
> 
> 
> 
> 
> 
> 
> 
> 
> you will also under sample blue wavelengths starting at 475nm and less (royal blue on down).
> 
> Lastly you will slightly over sample blue/greens to yellow/reds (orange) though this is minor.
> 
> Over all the error will not be critical.. but it would w/ measuring a light w/ 35% 660nm red and 66% high K white (6500K or better)
> 
> My "big dig" is I'm pretty sure apogee can "do better" if not to Li-Cor quality.. close to..
> They use a cheap IR "cut" filter AFAICT which cuts too soon.
> Apogee's inaccuracies are well noted w/ LED's and other "broken spectrum" lighting..they jut get a tad more crucial w/ LED.
> 
> you may only have, say, a 10-15% under-sample..
> 
> I would be the first to admit I'm a bit anal on this point.


So in simplicity term, worst case scenario would be 10-15% off if you have 35% red (no, only 10-15% red in my set-up) and 66% high K white (No again, mine is a two channels one is 40% warm, 30% 7000k, and the rest is with cyan red, blue). 

So I guess my apogee is good to go


----------



## jeffkrol

mba said:


> So in simplicity term, worst case scenario would be 10-15% off if you have 35% red (no, only 10-15% red in my set-up) and 66% high K white (No again, mine is a two channels one is 40% warm, 30% 7000k, and the rest is with cyan red, blue).
> 
> So I guess my apogee is good to go


If you had 35% 660nm red @50% it would be 35x.5 = 17.5% low..



apogee is fine and since it is common in the real world.. you will be able to at least compare to others (Finnex is all Apogee measurements).

Just keep in mind it will be a bit low..
Certainly beats a Lux meter or an "eyeball"..


----------



## mba

Sweet thanks!!


----------



## Hoppy

jeffkrol said:


> If you had 35% 660nm red @50% it would be 35x.5 = 17.5% low..
> 
> 
> 
> apogee is fine and since it is common in the real world.. you will be able to at least compare to others (Finnex is all Apogee measurements).
> 
> Just keep in mind it will be a bit low..
> Certainly beats a Lux meter or an "eyeball"..


I think Finnex used a contractor to test their lights, and he used the LiCor PAR meter. That contractor no longer does this for them, so they haven't tested the Planted Plus and published a nice set of charts for them. (I'm relying on my memory for this.:icon_frow)


----------



## jeffkrol

Hoppy said:


> I think Finnex used a contractor to test their lights, and he used the LiCor PAR meter. That contractor no longer does this for them, so they haven't tested the Planted Plus and published a nice set of charts for them. (I'm relying on my memory for this.:icon_frow)


Your memory and mine contradict a bit:


> Finnex uses Apogees on their other models. The only data they've published for the Planted + was measured for them by a University research lab, not their Apogee. It was also performed on a pre-production sample of the 24" model, so those numbers are also of limited value. They've got access to a LiCor now, so any future numbers should be reasonably accurate


http://www.plantedtank.net/forums/showthread.php?t=721441&highlight=finnex+par+apogee



> Sorry guys we've been trying to find a new source to get real PAR numbers. We lost our contact in the agriculture dept at one of our local community colleges that had the equipment to get precise data. We do have an apogee but the numbers on the planted+ will certainly be higher than the readings it provides, especially now with the 660nm true red leds.


----------



## mattinmd

jeffkrol said:


> Your memory and mine contradict a bit:


Technically, it was a university agricultural department, not a contractor.

http://www.plantedtank.net/forums/showpost.php?p=4803857&postcount=4

Being a university lab, I would also suspect they used substantially more advanced equipment than a cheap little LiCor... University labs usually have access to equipment well beyond the $2000 price range, at least if they're at all well funded. 

Universities also usually have rules prohibiting staff from helping commercial businesses "on the side", as it eats into sources for research grant money. This is probably why that ended. Of course the university would love to help Finnex if they provided a few hundred thou for a research grant. All in the name of advancing science, of course..


----------



## jeffkrol

mattinmd said:


> Technically, it was a university agricultural department, not a contractor.
> 
> http://www.plantedtank.net/forums/showpost.php?p=4803857&postcount=4
> 
> Being a university lab, I would also suspect they used substantially more advanced equipment than a cheap little LiCor... University labs usually have access to equipment well beyond the $2000 price range, at least if they're at all well funded.
> 
> Universities also usually have rules prohibiting staff from helping commercial businesses "on the side", as it eats into sources for research grant money. This is probably why that ended. Of course the university would love to help Finnex if they provided a few hundred thou for a research grant. All in the name of advancing science, of course..


LiCor is university standard for PAR.. I'm sure Finnex didn't want a spectroanalysis
http://www.jstor.org/discover/10.2307/2389327?sid=21106227547913&uid=3739976&uid=2&uid=4&uid=3739256

Point is "we" don't even know which ones were or were not tested by the Uni..and which were tested by Finnex w/ "their" Apogee


----------



## mattinmd

jeffkrol said:


> LiCor is university standard for PAR.. I'm sure Finnex didn't want a spectroanalysis
> http://www.jstor.org/discover/10.2307/2389327?sid=21106227547913&uid=3739976&uid=2&uid=4&uid=3739256


Fair enough... didn't realize universities were using that as a standard.



jeffkrol said:


> Point is "we" don't even know which ones were or were not tested by the Uni..and which were tested by Finnex w/ "their" Apogee


AFAIK, all the numbers that Finnex has published for final products to date have been Apogee numbers. I think it is only the one pre-production Planted+ that got the University involved, because of the 660nm issue.

I could be wrong of course, but that is my general impression.


----------



## jeffkrol

mattinmd said:


> AFAIK, all the numbers that Finnex has published for final products to date have been Apogee numbers. I think it is only the one pre-production Planted+ that got the University involved, because of the 660nm issue.
> 
> I could be wrong of course, but that is my general impression.


That is my assumption as well..


----------



## Filet-O-Fish

Hi Everyone.
This is my first post here. 
I have read from the first page till here and all my previous ideas of lighting for a planted had been blown away. I have always thought the WPG was the right way but now I realize that its not any more.

So I have this problem for my planted tank's lighting.

I have just purchased a T5HO light set.
It can hold 6 pieces of 48" T5HO at 54 watts each. I have also bought six Odyssea brand tubes.
4 pcs - 6400K
1 pc - 10000K
1 pc - red plants ( no K reading on tube)

The light set has individual mirror like reflectors for each T5.
The light set comes with 3 light settings:

a. 2 T5s can be switched ON
b. 4 T5S can be switched ON
c. All 6 T5s can be switch ON.

My tank is (H)48" by (W)18" by (H)22"
Volume: 80 gallons
Co2: Injected Co2
Fertilizers: EI dosing

The light set is now on a adjustable hanging stand. 
The light is 8" from the top of the tank and 25" from the substrate level.

According to the graph posted by Hoppy, the Odyssea 2 bulb T5HO 36" is only 35 PAR. 
Will the PAR be same for my light set at 25 inches from the substrate?

I intend to go for mid to high light tank.

I'm confused on the exact height I should have my light set and would appreciate the tips or advice given.
Thank you very much.


----------



## jeffkrol

I'm confused why youare wondering about the PAR of 2 bulbs.. You have 6.


----------



## Filet-O-Fish

jeffkrol said:


> I'm confused why youare wondering about the PAR of 2 bulbs.. You have 6.


Hi Jeff 
I'm confused as well. 
Understanding PAR is new to me.
Anyway, what is your opinion of my lighting issue?

Is the height of 25 inch from the substrate for a 4 T5HO considered mid or high light?

Thanks


----------



## jeffkrol

Filet-O-Fish said:


> Hi Jeff
> I'm confused as well.
> Understanding PAR is new to me.
> Anyway, what is your opinion of my lighting issue?
> 
> Is the height of 25 inch from the substrate for a 4 T5HO considered mid or high light?
> 
> Thanks



you could have par in the range of 60-90.. considered high-ish..








http://www.plantedtank.net/forums/showthread.php?t=105774


----------



## mattinmd

Hmm,

I'd assumed Filet-o-Fish was using an Odyssea fixture, but looking back that's not explicitly stated, just that the bulbs are Odyssea.

Regardless, if they are using an Odyssea brand fixture with Odyssea bulbs, the 35 PAR should be roughly accurate.


----------



## Hoppy

Not all reflectors are the same. The very good ones will show you at least one full image of the bulb on each side of the bulb when you look up at the light. That almost triples the amount of light the bulb emits, since each reflection is almost the same as another bulb. But, poor reflectors have only a small effect on how much light the bulb provides. You need to look at the pictures of typical reflectors in the first post here and see how yours fits in. If it is a very good one you probably will get about 50 PAR at 25 inches. That would be medium light. If that's what you want, then two bulbs should be all you need.


----------



## Raymond S.

Hello Hoppy,
I have a T8 fixture which obviously has a very poor reflector. It's on a 10g tank.
Dwarf Sag barely grows/w it, but Water Sprite does well.
I do have a Mom & Pop LFS where I could buy one of those strip lights used.
If I were to paint the inside of it, what color would help best ?
In easy to find spray paint Aluminium/White are common. Might find Silver at
Hobby Lobby.
The first page(my forum parameters limit a page to 20 post)of this thread suggest
to me that if PAR is actually what the plant uses(as opposed to Lux) then each
bulb, by brand and part number of that brand is a different PAR ?


----------



## jeffkrol

Raymond S. said:


> Hello Hoppy,
> I have a T8 fixture which obviously has a very poor reflector. It's on a 10g tank.
> Dwarf Sag barely grows/w it, but Water Sprite does well.
> I do have a Mom & Pop LFS where I could buy one of those strip lights used.
> If I were to paint the inside of it, what color would help best ?
> In easy to find spray paint Aluminium/White are common. Might find Silver at
> Hobby Lobby.
> The first page(my forum parameters limit a page to 20 post)of this thread suggest
> to me that if PAR is actually what the plant uses(as opposed to Lux) then each
> bulb, by brand and part number of that brand is a different PAR ?


LUX is a subset of PAR..Arguably over sampling in bandwiths that are underutilized by plants.. 

White paint w/ barium sulfate added is the most economical reflective surface w/ little absorption in any wavelength..
http://www.triticeaecap.org/wp-content/uploads/2011/12/Barium_Sulfate.pdf



> each
> bulb, by brand and part number of that brand is a different PAR ?


Generally speaking but less of an issue than poor reflectors or too low drive currents or poor match..

You have littel control over say, different lots of the same bulb. Theoretically it would be a lot less a problem than say different brand 6500k bulbs..


----------



## Filet-O-Fish

Hoppy said:


> Not all reflectors are the same. The very good ones will show you at least one full image of the bulb on each side of the bulb when you look up at the light. That almost triples the amount of light the bulb emits, since each reflection is almost the same as another bulb. But, poor reflectors have only a small effect on how much light the bulb provides. You need to look at the pictures of typical reflectors in the first post here and see how yours fits in. If it is a very good one you probably will get about 50 PAR at 25 inches. That would be medium light. If that's what you want, then two bulbs should be all you need.



Hi Hoppy,
Thanks for your reply. Its good to know I have 50+- PAR which would be in the medium light range. Just to reconfirm, I'm using 4pcs of T5HOs now with a lighting period of 6 hours. So this 50 PAR is from 4pcs T5HOs right or is it from 6pcs? 

I posted a photo of the T5 light set below. The reflects are the exact same type as in the photo ( mirror like finish)

Thank you very much.











Bump:


mattinmd said:


> Hmm,
> 
> I'd assumed Filet-o-Fish was using an Odyssea fixture, but looking back that's not explicitly stated, just that the bulbs are Odyssea.
> 
> Regardless, if they are using an Odyssea brand fixture with Odyssea bulbs, the 35 PAR should be roughly accurate.


Hi Mat

Thanks for your info.
I have posted a photo of the reflectors in the above post.

The light set which is another brand can hold upto 6 T5hos. The LFS where I bought the set from had only Odyssea brand T5s at that moment. Sadly in my country, T5 lights are not carried by many LFSs.

I have noticed that in Odyssea light sets the reflectors are just one long flat piece of shiny metal.


----------



## Raymond S.

jeffkrol said:


> LUX is a subset of PAR..Arguably over sampling in bandwiths that are underutilized by plants..
> 
> White paint w/ barium sulfate added is the most economical reflective surface w/ little absorption in any wavelength.
> 
> Thank you for this...
> 
> But on this one...
> Unfortunately few manufacturers have spectrum charts/w their bulbs.
> But Zoo Med does and sometimes Coralife does.
> Not really concerned/w different lots of same bulb. Just under the impression that the red part of the spectrum is essential/critical to plant growth and just noticed that the Zoo Med Ultra sun has little/none of it.
> Compare their chart for the Flora and the Ultra sun bulbs. For years I have known that the Flora grows plants very well. But it has poor at best visible light. So using an Ultra sun for a main light so I can see in my tank and
> a Flora for the second,shorter photo period bulb is not the best option in my mind as plant growth goes, yet best for visibility in the tank.
> Perhaps I'm overly apprehensive about the lack of red in the Ultra sun.
> 
> "You have littel control over say, different lots of the same bulb. Theoretically it would be a lot less a problem than say different brand 6500k bulbs..."


----------



## jeffkrol

Raymond S. said:


> jeffkrol said:
> 
> 
> 
> LUX is a subset of PAR..Arguably over sampling in bandwiths that are underutilized by plants..
> 
> White paint w/ barium sulfate added is the most economical reflective surface w/ little absorption in any wavelength.
> 
> Thank you for this...
> 
> But on this one...
> Unfortunately few manufacturers have spectrum charts/w their bulbs.
> But Zoo Med does and sometimes Coralife does.
> Not really concerned/w different lots of same bulb. Just under the impression that the red part of the spectrum is essential/critical to plant growth and just noticed that the Zoo Med Ultra sun has little/none of it.
> Compare their chart for the Flora and the Ultra sun bulbs. For years I have known that the Flora grows plants very well. But it has poor at best visible light. So using an Ultra sun for a main light so I can see in my tank and
> a Flora for the second,shorter photo period bulb is not the best option in my mind as plant growth goes, yet best for visibility in the tank.
> Perhaps I'm overly apprehensive about the lack of red in the Ultra sun.
> 
> "You have littel control over say, different lots of the same bulb. Theoretically it would be a lot less a problem than say different brand 6500k bulbs..."
> 
> 
> 
> Over time I've painstakingly softened my approach on red per se..
> Looking at it this way:
> for shallow water plants red is an integral component of "natural" light. BUT that doesn't mean it is "perfect" only it is what they are used to dealing with.
> so the whole red thing gets complicated.
> 
> What is fairly known is that high blue w/ little red has the ability to change a plants morphology.. i.e stunt or stretch, bigger leaves or smaller. It also has an ability to change pigment contents.. high blue more xanthrophylls ect (more red pigments) but without red light you don't "see" them as well.
> 
> Bottom line red is probably more crucial to a balanced "look" plant wise and human vision wise then it is to plant survival and growth.
> 
> Thinking about nature.. if you go to a clearwater lake and look 10ft down and see plants, they see little to no red. But what else do you see, maybe one plant variety or 2.. The ones that can "survive" without red.. Would they be happier in shallow water? More than likely..
> Would they grow better and slightly different w/ more red.. Probably..
> 
> 
> 
> 
> 
> 
> 
> 
> 
> 
> 
> 
> 
> 
> 
> 
> 
> 
> 
> 
> 
> 
> 
> Click to expand...
Click to expand...


----------



## V1peR

I would like to have the highest light possible using my setup (co2+seachem ferts + dirt substrate)

At the moment i have 2 T5HO bulbs at 16 inches from the substrate.
But i would like to use all of my 4 Bulbs (by raising the lighting unit).
This way I will be able to create different spectrums using different kelvin tubes (was think of 1 3000k, 1 4000 kelvin and 2 6500 kelvin)

How much should I raise my lighting unit to achieve this "high" light with 4 T5HO?


----------



## burr740

V1peR said:


> I would like to have the highest light possible using my setup (co2+seachem ferts + dirt substrate)
> 
> At the moment i have 2 T5HO bulbs at 16 inches from the substrate.
> But i would like to use all of my 4 Bulbs (by raising the lighting unit).
> This way I will be able to create different spectrums using different kelvin tubes (was think of 1 3000k, 1 4000 kelvin and 2 6500 kelvin)
> 
> How much should I raise my lighting unit to achieve this "high" light with 4 T5HO?


Without knowing more about your fixture, ie reflectors etc, here's mine @ ~24 inches. Bulbs are one actinic, one 3000K, one 6700K and a 6500K.


----------



## V1peR

burr740 said:


> Without knowing more about your fixture, ie reflectors etc, here's mine @ ~24 inches. Bulbs are one actinic, one 3000K, one 6700K and a 6500K.



I forgot mentioning reflectors, I have crappy ones, just a chrome foil that is behind the tubes, nothing fancy at all.

Are those PAR or LUX? 
131 PAR are a lot of light I like that !


----------



## burr740

Par


----------



## mlongpre dxYh

130 par at substrate? Man how much co2 are you pumping in? Do you have fish? I'm finding it hard to get my plants to grow with only 50 par. Curled gnarled tiny leaves is all I seem to be able to grow. 

I'm finding it hard when I see such high par tanks with amazing growth. 5kh water and I drop the ph down to 6.1 and it stays there all day. That combined with 50 par and ei is giving what looks to be like co2 deficiency. I can't fathom how it would even be possible to get enough co2 in the water with such high par. Also use 5kh drop checker that turns yellow green.


----------



## mattinmd

Tiny curled leaves sounds more like a nutrient deficiency than too much light... Calcium deficiency immediately pops to mind when you're talking twisted growth...

Too much light causes photoburn, but that's *really* hard to do with our aquarium lights... Full noon sunlight is around 2000 PAR, depending on where you live and what time of year you're talking. 50 PAR isn't going to photoburn anything other than mushrooms and maybe the most sensitive of ferns. 

Also photoburn first starts off looking like dark brown patches forming on the leaves, like this basil plant:

ie: http://forums.gardenweb.com/discussions/1937629/whats-wrong-with-my-basil


----------



## mlongpre dxYh

Yeah I've been trying to figure this one out for almost a year now. Been very frustrating. My water quality report for the city of Toronto Canada says that I should have enough Ca and Mg. 35 and 9 ppm respectively. Is that enough of those nutrients. 

Sorry I feel like I'm jacking the thread. I'll create a new one.


----------



## Wilderman204

Sry if it's been asked or posted already, but any par value information on the "Fluval Aqualife&plant LED"?? I'm running the 25w model on a 20high. Killer thread btw!!!


----------



## burr740

mlongpre dxYh said:


> 130 par at substrate? Man how much co2 are you pumping in? Do you have fish? I'm finding it hard to get my plants to grow with only 50 par. Curled gnarled tiny leaves is all I seem to be able to grow.
> 
> I'm finding it hard when I see such high par tanks with amazing growth. 5kh water and I drop the ph down to 6.1 and it stays there all day. That combined with 50 par and ei is giving what looks to be like co2 deficiency. I can't fathom how it would even be possible to get enough co2 in the water with such high par. Also use 5kh drop checker that turns yellow green.


Not sure how much CO2, PH drops about 1.2. Yes I have fish, one gourami and several Pristellas, neons, ottos flying foxes, etc. I dose full EI and do 50% weekly water changes...at least. Sometimes every 4-5 days. Also have pretty good surface agitation (you can see in that one pic) and and flow throughout.

50 PAR will grow just about anything, assuming other conditions are met. I have a lot of these same plants in another tank about 50 PAR using only Excel, no CO2.

Honestly, I didnt even realize I had this much PAR until I got that meter a few weeks ago. Always assumed it was in the 80-90 range. I would raise it up some but my homemade mounting bracket only goes this high. And since it aint broke, so to speak...


----------



## mattinmd

Wilderman204 said:


> Sry if it's been asked or posted already, but any par value information on the "Fluval Aqualife&plant LED"?? I'm running the 25w model on a 20high. Killer thread btw!!!


This is the best I can find, which is a "heat map" graph of PAR for the 48" fixture at 6" depth:

http://www.plantedtank.net/forums/showpost.php?p=4704986&postcount=39


----------



## V1peR

burr740 said:


> Par



Ok so with my crappy reflectors I might be able to get 90-100 par at 24 inches, i will do that tomorrow , I hope I don't get an algae bloom !


----------



## niza

I have a 24 inch Current USA SunDial T5 HO 4x24W fixture: 
http://www.marinedepot.com/24_inch_...xtures-Current_USA-CU01150-FILTFIT54U-vi.html

And a 6,700K T5 Fluorescent Lamp - 14 W - 24" bulb:
http://www.bigalspets.ca/6-700k-t5-fluorescent-lamp-14-w-24.html

The light fixture is 13 inches from the top of the gravel.

According to my calculations, I have about 27 PAR. Are my calculations right?


----------



## burr740

Im confused niza, are you running the T5NO bulb(s?) in the HO fixture? or is that in addition to the 4 T5HOs?

That SunDial unit looks like it has pretty good reflectors, at 13" your probably in the 140+ range with 4 T5HOs


----------



## niza

burr740 said:


> Im confused niza, are you running the T5NO bulb(s?) in the HO fixture? or is that in addition to the 4 T5HOs?
> 
> That SunDial unit looks like it has pretty good reflectors, at 13" your probably in the 140+ range with 4 T5HOs


I apologize for the confusion. I am only running one T5 bulb in the fixture (you have the specs above). What do you think?


----------



## mattinmd

Wait,

That bulb, at 14 watts, is a T5NO bulb.
That fixture is a T5HO fixture, and needs a 24 watt bulb..

These two things aren't supposed to be used together.


----------



## niza

Ups, you are right!

I decided not to use that fixture any more since I want to have a low tech tank and I am not able to use any lower wattage bulbs.

I will use the cheap fixture that came with the tank and add 2 x 13W cfo bulbs.


----------



## duce

Im trying to figure out what lights to get for my new tank and dont want to waste money by buying the wrong lights again. 

If i want high lighting with pressurized CO2 to be able to grow whatever takes my fancy in a tank 150cm long 50 wide and 60 tall would i be better of with a 4 bulb odyssea t5ho or 3 70w or 150w odyssea 45cm metal halides.


----------



## Hazol

burr740 said:


> Without knowing more about your fixture, ie reflectors etc, here's mine @ ~24 inches. Bulbs are one actinic, one 3000K, one 6700K and a 6500K.


How do you measure par with a lux meter? Because that's what I see on the picture.


----------



## mattinmd

Hazol said:


> How do you measure par with a lux meter? Because that's what I see on the picture.


You modify the sensor's filters to be spectrally flat (or at least closeish) instead of scotopically weighted, then re-calibrate for PAR. (and modify the sensor to be waterproof). Some versions replace the sensor end entirely.

There's plenty on this in the DIY section, Hoppy has made a couple different models.

http://www.plantedtank.net/forums/20-diy/453225-diy-par-meter.html

If you look in the picture you can see the cable has been spliced at the end of the original coily-cord with a thicker cable, a tell-tale sign this is a modded meter which has replaced the whole sensor end.


----------



## Argus

mattinmd said:


> You modify the sensor's filters to be spectrally flat (or at least closeish) instead of scotopically weighted, then re-calibrate for PAR. (and modify the sensor to be waterproof). Some versions replace the sensor end entirely.
> 
> There's plenty on this in the DIY section, Hoppy has made a couple different models.
> 
> http://www.plantedtank.net/forums/20-diy/453225-diy-par-meter.html
> 
> If you look in the picture you can see the cable has been spliced at the end of the original coily-cord with a thicker cable, a tell-tale sign this is a modded meter which has replaced the whole sensor end.


Has anyone looked at building a PUR/PAS meter? Seems like the only change would be the filters used. It might have to be limited to either a 400-500 nm sensor, or a 620-680 nm sensor. Perhaps both and put a connector near the meter.










I would find this useful because I'd like to know what the Planted + 24/7 is doing during its sunset, moonlight, and sunrise periods.


----------



## mattinmd

Pur is broader band than that, due to carotenes and other pigments in plants. Those graphs are of chlorophyll a and b when extracted from a plant and put in a test tube. 

Regardless, PUR is also somewhat plant specific. Different species have different PUR curves, so that isn't practical unless you pick one specific plant.

I suggest looking at the typical plant response curve at. 
http://www.apogeeinstruments.com/comparisons-in-quantum-sensor-output-for-different-light-sources/


----------



## jeffkrol

Argus said:


> Has anyone looked at building a PUR/PAS meter? Seems like the only change would be the filters used. It might have to be limited to either a 400-500 nm sensor, or a 620-680 nm sensor. Perhaps both and put a connector near the meter.
> 
> 
> I would find this useful because I'd like to know what the Planted + 24/7 is doing during its sunset, moonlight, and sunrise periods.


The "hardware" already exists (at a cost) but the interpretation is the problem.
https://www.ephotozine.com/article/sekonic-spectromaster-c-700-and-c-700r-26468










and as Matt said.. PUR is problematic due to a few complications.

Even PAR as measured is a compromise and its main purpose (even response from 400-700nm) is more for comparative purposes than "absolutes"..

BTW somewhere there is a version that does PAR..
But even w/out that.. I dream about owning this meter.. why? .. who knows..


> The C-700 series incorporates a CMOS linear sensor, that measures and evaluates the true color temperature of a light source from 380
> to 780 nanometers (nm) in 1 nm output wavelength increments. What makes the C-700 series truly unique and exceptional is its ability
> to not only measure conventional light sources but also emerging light source technology. Its exclusive ability to measure in 1 (nm) i
> ncrements captures spikes in light source output, especially fluorescent and LED sources, providing unmatched color measurement
> accuracy.


----------



## burr740

Hazol said:


> How do you measure par with a lux meter? Because that's what I see on the picture.


matt explained it. That one was made by @Hoppy (thanks again man, it's been so very useful!)


----------



## jeffkrol

Addendum to my post above.. The Minolta, I believe, has a PAR model..

Measuring Light in Greenhouses with the CL-500A Illuminance Spectrophotometer

Measures PPFD.. Now all you need is a portable sensor or fiber optic feed..


http://www.konicaminolta.com/instruments/download/catalog/light/pdf/cl500a_catalog_eng.pdf


----------



## Argus

jeffkrol said:


> The "hardware" already exists (at a cost) but the interpretation is the problem.
> https://www.ephotozine.com/article/sekonic-spectromaster-c-700-and-c-700r-26468
> 
> 
> 
> 
> 
> 
> 
> 
> 
> 
> and as Matt said.. PUR is problematic due to a few complications.
> 
> Even PAR as measured is a compromise and its main purpose (even response from 400-700nm) is more for comparative purposes than "absolutes"..
> 
> BTW somewhere there is a version that does PAR..
> But even w/out that.. I dream about owning this meter.. why? .. who knows..


That's a pretty cool toy. Love to have it for photography as well. Too bad it costs as much as my entire aquarium setup. 

The problem I have with PAR is that a light with a lot in the green area of the spectrum could read high, but be of little value for plants. A light strong in blue and green could be better for plants, but have a lower PAR reading. 

Nitpicking the slight differences in plants is not going to matter that much for a meter than measures 400-500 and 600-700 nm. It is still going to give you a better idea than reading everything from 400 to 700. I think some sort of green/yellow blocking filter would be useful, however a spectrometer would be so much better. 

The American Physical Society has put a free app on iTunes turns your iPhone into spectascope. Someone needs to create a spectrometer app.


----------



## jeffkrol

Argus said:


> Nitpicking the slight differences in plants is not going to matter that much for a meter than measures 400-500 and 600-700 nm. It is still going to give you a better idea than reading everything from 400 to 700. I think some sort of green/yellow blocking filter would be useful, however a spectrometer would be so much better.












Granted that "may" be somewhat correct but the area between 500 and 600nm is not exactly insignificant..

using the spectrophotometer and weighing the bandwidths is certainly doable in software, once the hardware is calibrated..

As to doing it w/ the current photodiodes, there is enough problems w/ poor spectral response on both ends to begin with..

Plants also can adapt to the light spectrum and as noted earlier, the above curve is a "composite" response and used mostly (if not all) terrestrial higher plants..
Species specific spectrum studies are few and far in-between. it is not exactly a "paying" area of research.. 
The tech to do what you would like it to do is already created.... and really has been for quite sometime..I've suggested using "camera chips" as a PAR meter before and really that is the "guts" of those expensive meters..

Using a fiber optic "pipe" and this:
http://www.instructables.com/id/DIY-Spectrometer-Explore-the-Unknown-/?ALLSTEPS

figuring out the sensitivity problems (all silicon is fairly blue in-sensitive) and "doing the calculus" on area distribution and done.. 

It is interesting because making a "flat response" sensor is difficult enough then reconfiguring 
again for the spectral inefficiencies w/ filters does start to pose a sensitivity hit on the diodes.. as in each filter cuts out gross response.
Nothing insurmountable and I certainly wouldn't discourage it but question the added errors to an already flawed system at "our" level.. 










since you mentioned photography, I assume you are aware that digital photo channels are "fudged" for this very reason.
In the RGB Bayer array the green channel multiplier is usually one while red/blue can be 1.3-2.5x the analog signal.
https://stephenstuff.wordpress.com/2014/01/05/an-introduction-to-digital-white-balance/

to add a bit more data to the picture though..


> So evolution has provided chlorophyll a with a range of other pigments, antenna pigments, that absorb higher-energy wavelengths and pass the absorbed energy on to chlorophyll a. Thus plants can utilize light from every wavelength in the visible spectrum from 400 to 700 nm. This is best observed by examining the action spectrum for a particular plant:












http://plantphys.info/plant_biology/photopart.shtml


----------



## livins

what I usually do is. Look at the substrate if the light penetrates a few layers of the aqua sand. The intensity is good enough. If I have enough money I will sure try your method one day. Untill then trimming with home scissors and planting with my hair pulling tweezer my wife has.


----------



## Trigger334

Here's a recent article, which covers all the important aspects of aquarium LEDs, including PUR, and the science behind it. The website also reviews many of the more popular aquarium LEDs out.

LED Aquarium Lights,[censored]Lighting; How they work, DIY | Aquarium Article Digest

Here's a good review as well.









TMC AquaRay Vs. Build My LED | Marine Aquarium LED Study


----------



## jeffkrol

Trigger334 said:


> Here's a good review as well.
> 
> 
> TMC AquaRay Vs. Build My LED | Marine Aquarium LED Study


I've read this before:


> AquaRay has licensed emitters, which no one, including BML cannot get. They are the Cree 6500K xb-ds.


It means nothing really, without an explanation of the difference...
Oddly enough the "normal" Cree xb-d w/out the "s"
http://www.cree.com/LED-Components-and-Modules/Products/XLamp/Discrete-Directional/XLamp-XBD



> Smallest lighting-class LED enables dramatically lower system cost


----------



## Trigger334

jeffkrol said:


> I've read this before:
> 
> 
> It means nothing really, without an explanation of the difference...
> Oddly enough the "normal" Cree xb-d w/out the "s"
> Cree XLamp XB-D LEDs


The AquaRay have the Cree XB-D. The (s) is just plural. Guess that should be made more clear. The link you provided are the emitters, which are licensed, meaning TMC had Cree make them and by contract, cannot be sold to any other brands. 
http://www.plantedtank.net//www.pinterest.com/pin/create/extension/


----------



## jeffkrol

Trigger334 said:


> The AquaRay have the Cree XB-D. The (s) is just plural. Guess that should be made more clear. The link you provided are the emitters, which are licensed, meaning TMC had Cree make them and by contract, cannot be sold to any other brands.


Between luminous flux groups and performance groups, there are literally dozens of variation on one "color" class. As I said really meaningless
for all we know they could have the "exclusive use" of the reject class..  :


----------



## Trigger334

jeffkrol said:


> Between luminous flux groups and performance groups, there are literally dozens of variation on one "color" class. As I said really meaningless
> for all we know they could have the "exclusive use" of the reject class..  :


I suppose if someone is the type that looks at the world as a glass half empty and also doesn't take any of the other information in the article into context, I guess that's a point.

Considering there's a lot of evidences to show the qualities of the fixture, I don't see how someone can come to this conclusion, unless they are specifically trying to nit-pick the brand. Like the fact, the reef models also have not just a licensed emitter, but a patented emitter, which is the most advanced emitter out period (The way it looks and the energy it provides to the tank are different, you get high energy dark blue/purple energy, while it being a light blue appearance) by Osram Oslon. Or the fact they have the highest water proof rating, or the longest warranty, or that they are the largest house-hold name in the UK.... Basically everything that was in the article. If you just disregard everything in the article and try to say the emitters are meaningless, even though there's spectrum information about the emitter out... 

I don't get the picture you linked too... All it does show the xb-d's are the most advanced from Cree, which is in AquaRay favor. The fact the AquaRay has a true 6500K emitter, not a combination of cool white and colors (even if they too are xb-d's), it's a huge aspect for AquaRay..
http://www.plantedtank.net//www.pinterest.com/pin/create/extension/


----------



## jeffkrol

Trigger334 said:


> I suppose if someone is the type that looks at the world as a glass half empty and also doesn't take any of the other information in the article into context, I guess that's a point.


no the point is "exclusive emitters" w/out any FACTS as to why that is "important" is not looking at things half full or empty.. JUST as completely empty of any meaning..

Whether the fixture performs well or not is not an issue at all..

sorry, I work in retail, pretty sensitive to "sizzle w. no steak" statements..

BTW: Luxeons are, arguably, better than CREE's anyways..  

Why don't you ask them what is special about them.. be technically specific..

more fluff "true 6500k" emitters..
every decent LED manuf. has a bin w/in the "true 6500k" range..

The picture shows the amount of variation (from spectrum, to efficiency, to voltage characteristics ect.) possible in a single "class" of LED..

you are correct though that manuf. can request a very specific bin. It is good for product consistency. AND one does pay extra for that.

On another note.. CREE outsources a lot of their LED production. not all CREE's are equal.. 




> All of them will work, but only Bridgelux and Philips will have good, consistent color. Getting a Cree chip with good color is like pulling teeth.


http://www.reefcentral.com/forums/showthread.php?t=2376772


----------



## Trigger334

jeffkrol said:


> no the point is "exclusive emitters" w/out any FACTS as to why that is "important" is not looking at things half full or empty.. JUST as completely empty of any meaning..
> 
> Whether the fixture performs well or not is not an issue at all..
> 
> sorry, I work in retail, pretty sensitive to "sizzle w. no steak" statements..
> 
> BTW: Luxeons are, arguably, better than CREE's anyways..
> 
> Why don't you ask them what is special about them.. be technically specific..
> 
> more fluff "true 6500k" emitters..
> every decent LED manuf. has a bin w/in the "true 6500k" range..
> 
> The picture shows the amount of variation (from spectrum, to efficiency, to voltage characteristics ect.) possible in a single "class" of LED..
> 
> you are correct though that manuf. can request a very specific bin. It is good for product consistency. AND one does pay extra for that.
> 
> On another note.. CREE outsources a lot of their LED production. not all CREE's are equal..
> 
> 
> 
> 
> LED output comparison quick reference (Bridgelux, Cree, Philips) - Reef Central Online Community


You yourself linked to Cree's website, which shows why they're the more advanced LEDs by Cree. They're more high power, with less energy used. Meaning less energy can be used to have the same/better growth. Plus they are meant to be driven harder, without wearing out. Many brands drive the emitters at much less mA to preserve the life of the emitter. Plus they can handle more moisture electrical variances, since we're basically hanging computers over aquariums (all described in the article...) 

That's the stake... and still, you're focused on just one point... Even without this point, there's others, which set AquaRay above BML.

No one else is using the xb-d's except for maybe BML (a couple UK brands too), but they don't publish what emitters they use. They just have XB in the fixture title, so it's an assumption. 

That aside, most brands, including BML, combine cool white (5500K xbd?), with color emitters to make "6500K". Which is why the statement is made that AquaRay uses true 6500K, because they use just use one type of HO emitter with the 6500K rating. Throughout aquatic history, 6500K has show to have some of the best growth (better than 5500k) and even has additional benefits to aquatic life... That cannot be said for combinations as it's not natural and I don't believe any studies have been done. Plus, placement of the color emitters can have affect on growth under that emitter as well, even though claims are made that colors blend when in water.

About Luxeons, I cannot say. What I do know, the most popular fixtures out are not using them. Maybe you know a brand that's using them though. If there's a fixture with Luxeon 6500Ks, with some more perks to make them comparable to AqauRay...Great. There needs to be more quality LEDs out. 
http://www.plantedtank.net//www.pinterest.com/pin/create/extension/


----------



## jeffkrol

That is because I am NOT attacking the light .. only the pointless selling point of "secret sauce" Cree's..
And no CREE has, arguably, but fairly certain, poor spectral performance w/ their white diodes..i.e color shifts off axis as compared to Phillips.. "historically".. 

http://cireon.com/case_study/cree-vs.-luxeon
http://cireon.com/pdf/Case_Study,_Cree_vs_Luxeon,_with_Cree_LM-79s.pdf









now in all fairness that is "older" CREE's.. I understand that but a bit of real world:










http://www.aeonlighting.com/tw/upload/file/1398739749.pdf


----------



## jeffkrol

Me doth think you protest too much..... 

For fun;
http://www.mouser.com/pdfdocs/DS158.pdf
max 144lumens/watt..
i'll leave out the fact that 6500k is not "the ideal" color temp either.. 

just another opinion, not unlike mine..


> Yes. Bridgelux makes the best high-CRI white LEDs, but they're also ~29v at 700mA (and give over 1700 lumens), so you would need a different driver setup.
> 
> Cree makes high output LEDs, but their white LEDs that are readily available from places like RapidLED, LED group buy, etc are all low-CRI parts.
> 
> Lumileds chips have the same output as Cree, but their white LEDs are available in 85- and 90CRI versions and give excellent color.


soo "IF" they are using ..say.. high CRI "special CREE bins" then they should say so...


----------



## Trigger334

OK...you're stretching to make points and pulling from resources, which we don't know the credibility or how it even relates to any aquarium LED on the market.

You show me a better brand LED out... We can talk more. 

Someone that does their homework will see AquaRay to be one of the best aquarium LEDs out. A LED actually meant to be used over water, plus all the other perks.


----------



## jeffkrol

Trigger334 said:


> You show me a better brand LED out... We can talk more.
> 
> Someone that does their homework will see AquaRay to be one of the best aquarium LEDs out.


One that is subjective.. 2) you got to be kidding??

Show me ONE piece of independent data that would support such nonsense...

THER IS NO perfect light.. Kessil as an example; Crappy choice of freshwater specrum spectrum and as cryptic as Aquaray.. All talk w/ no technical backing..

sure they "grow stuff" So will about a thousand candles.. Means nothing actually.. 


Photons are photons.. NONE are "magical bins".. 
That is physics and science, not advertising voodoo..


besides, except for a few chouce LED's "just whites" (of almost any K have GIANT holes their spectrum..
Zero "violets", little cyan and little red above 650nm..

CREE family of whites (any brand is not different by much)


























feel free to give me all the Aquaray data you have..

"better brand" is certainly subjective. As a personal choice I'd pick In no particular order), Radions, Reefbreeders, DsunY, Current plus PRO, MANY easy and cheap DIY's, Some t5's, and even a "modified" Beamswork over them.. 
There are different reasons for each choice..

until you can tell me WHY they are exclusive , don't even bother replying to me.. you are just shilling.. no more no less..
christmas sales down????

tired of fighting w/ reefers????
http://www.reefcentral.com/forums/showthread.php?t=2391677&highlight=aquaray


----------



## Trigger334

Posting this for others who want to understand what makes a great LED.

Useful article, which goes over the science of what separates the different LEDs on the market. 

LED Aquarium Lights,[censored]Lighting; How they work, DIY | Aquarium Article Digest


----------



## jeffkrol

you tell me which one is better..


----------



## Trigger334

Jeff.

The GroBeam 1000 is not in production anymore. You will want to look at the GroBeam 1500 or Colorplus.

You certainly are set on emitters/spectrum. Fluval is a composite light as well. Meaning they mix white with colors to achieve their overall spectrum. Plus they have so many emitters, they have to be daisy chained together to keep the price low. Meaning the construction is among the poorest. No drivers, more watts, poor dimming method.

If the article was read, someone can see, that while they might get a decent spectrum, the fixture is set to fail in the near feature, which is why the warranty is so short. Dimming 0-10v with this many daisy chained emitters only increases the chances of fixture failure and gets higher and higher with more emitters. Fluval is one with the most emitters on the market. 0-10v applies so much stain to the circuity, more with more emitters, plus when moisture is involved, it's a set-up. 

It does have a "moisture guard", I'll give it that, but is not waterproof. Working in the industry, I can't even count how many times people have moisture issues with LEDs. I cannot also count how many times people fixtures have ended up in the water. A IP waterproof rating is much more desirable then a moisture guard.

So, while the spectrum might be nice. If someone can swing it, they are far better off investing in better tech, that will last them longer. Having to replace even one of these fixtures after their short 6mo? warranty, will end up costing you more than a decent BML or AquaRay. I'd recommend a BML over a Fluval.

If even one emitter goes out on the fixture, that will shift the spectrum as well. Really messing with the real growing power of the blues and reds.

Can't remember, these have a fan? That would say something as well.

I can see why you are set on emitters and spectrum. You appear to be a DIY guy? Fun stuff, while you have more spectrum control (which is debatable as to what is best, considering nature as well), that's about all DIY has going for it. Maybe make certain colors pop to the eye. They don't even end up costing less and much more time is involved. With no moisture control and no warranty. 

I still recommend people to read the article and learn the facts of an overall great LED.


----------



## jeffkrol

THE reason I'm "hung up" on coloredLED's is fairly self explanatory from the above diagram btw: 

now this "hang up" is BOTH for visual and plant benefits..

Soon all of this will be pointless as "true" high CRI diodes become more common..
BTW the Yuji uses "purple" as the base emitter not RB or blue..
Out of the 2 images below, which one will have better overall color rendition and cover all photosynthetic pigment peaks relatively even?




























High CRI LED Lighting | Yuji LED

see a "one color" emitter I like.. 

BTW: so much for "secret sauce" 6500k emitters.. See you can teach old dogs new tricks..












NOW if you can get them to use cyan instead of green.. (to start) we'd be getting close to being on the same page..
NOTE: CREE dosn't "do" cyan AFAICT.. but Phillips does..


----------



## Trigger334

Those printed spectrum are rather misleading anyways. You might be interested in this.


----------



## Malin

Did anyone ever check out the Aquael Leddy Tube 8000K? It looks interesting and I'm considering the 16W, but I can't find any information about PAR.

I need some more light for my 250l tank to supplement the 2xHagen Glo 39W, but I can't decide wether to buy another one or put in LED.


----------



## nofearengineer

Trigger334 said:


> Here's a recent article, which covers all the important aspects of aquarium LEDs, including PUR, and the science behind it. The website also reviews many of the more popular aquarium LEDs out.
> 
> LED Aquarium Lights,[censored]Lighting; How they work, DIY | Aquarium Article Digest
> 
> Here's a good review as well.
> 
> 
> 
> 
> 
> 
> 
> 
> 
> TMC AquaRay Vs. Build My LED | Marine Aquarium LED Study


Has Trigger mentioned that he wrote this review article? A bit disingenuous to post it as a reference without disclosing his bias.


----------



## Hoppy

Malin said:


> Did anyone ever check out the Aquael Leddy Tube 8000K? It looks interesting and I'm considering the 16W, but I can't find any information about PAR.
> 
> I need some more light for my 250l tank to supplement the 2xHagen Glo 39W, but I can't decide wether to buy another one or put in LED.


Wow! You must want really high light! A two bulb Hagen Glo light should be enough to grow most any plants. That size tank, with two 39 watt T5HO bulbs is sold as a reef tank, and reef tanks use a lot more light than planted tanks.


----------



## Diana

The K value is a number that represents what the bulb will look like to our eyes. 8000K is decidedly toward the blue. Usually planted tanks do well with some of the red wavelengths and some of the blue. Usually about 6500K is about as high a K value that works for plants.


----------



## Jeff5614

@;


Diana said:


> The K value is a number that represents what the bulb will look like to our eyes. 8000K is decidedly toward the blue. Usually planted tanks do well with some of the red wavelengths and some of the blue. Usually about 6500K is about as high a K value that works for plants.


That's interesting being that ADA says their bulbs are 8000K and yet seem to grow plants well. My Kessils have an adjustable range of 6000 to 9000. I have them set in the middle of the range which, I would think, puts me at 7500 and I have no issues with growth. It makes me wonder how accurate the Kevin ratings are from all of the manufacturers.


----------



## jeffkrol

Jeff5614 said:


> That's interesting being that ADA says their bulbs are 8000K and yet seem to grow plants well. My Kessils have an adjustable range of 6000 to 9000. I have them set in the middle of the range which, I would think, puts me at 7500 and I have no issues with growth. It makes me wonder how accurate the Kevin ratings are from all of the manufacturers.


Kelvin for certain types of lights (fluorescent,led, and MH for example) is an average.. therefore there is a very broad number of ind. "colors" and different intensities of each color that can create the same K value..
K and CCT are the same sort of..


> The correlated color temperature (CCT) is a specification of the color appearance of the light emitted by a lamp, relating its color to the color of light from a reference source when heated to a particular temperature, measured in degrees Kelvin (K).





> The correlated color temperature (CCT) designation for a light source gives a good indication of the lamp's general appearance, but does not give information on its specific spectral power distribution. Therefore, two lamps may appear to be the same color, but their effects on object colors can be quite different.


http://www.lrc.rpi.edu/education/learning/terminology/cct.asp


----------



## hachi

Does anyone know what the PAR is like on the updated Fluval Spec V? Thanks.


----------



## will5

So I lucked out and found a 48" 6xT8 fixture with individual reflectors for my 75g. I was wondering if this would be high light and grow carpet plants?


----------



## roadmaster

Would depend on how high over the tank the fixture will rest.
With PAR ,which is all plant's really care about,inches matter.
I think the fixture will/would be too wide to rest on the tank,(I have four tube fixture)so ... Par will be different as the light fixture is raised.


----------



## jeffkrol




----------



## Khoon2

Hi all you experts. I am here on this old post because i am unable to get an affirmative. So i want to do a diy led. My substrate is dirt and aquasoil mix and capped with sand. My tank is 6ft x 1.5ft x 1.5ft. I want to do a dwarf sag carpet and some swords and crypts. My intention is to put about three or four 4ft t8 led tubes. Staggered along the length to cover the 6ft. No co2 no reflectors needed. Will that work. Or do i need more or less tubes. The tube available to me are 20w 6500k cri 75 and direct 110v so no ballasts neither. The tubes are similar to these 
https://www.walmart.com/ip/Yescom-1...e-Replacement-Lamp-Bulb-Milky-Clear/104669279


----------



## Khoon2

Jeffkrol helped alot so far and was really one of the only 2 persons to assist.


----------



## jimclassic

Hoppy said:


> When light shines into an aquarium the air-water interface slightly focuses the light. Beams off center are refracted towards the center. This is why the PAR around the center of the tank goes up when you add water. Near the glass at the front, back, and ends, there is considerable reflection of light back into the tank from the glass-air interface, which increases the PAR near the glass. But, if the glass is less than perfectly clean on either side of the glass the amount reflected back into the water is decreased. As I recall I did those PAR measurements in a 10 gallon tank, which I didn't take pains to clean thoroughly. The glass must have been non-uniformly dirty. This was a few years ago, so my memory of that isn't perfect.
> 
> I don't have either a 30 inch long tank, nor a 24 inch long light to do PAR tests with. Most of the data I have comes from others who either post it or PM it to me. Someone with the right tank and light, and access to a PAR meter, needs to do that testing. One thing I do know is that if you raise the light far enough above the top of the tank a short light can light up a tank well enough for our purposes. In fact one good way to light a tank is to use a short, but very bright light (4 bulb T5HO, for example) suspended a foot or more above the tank. That greatly reduces the difference in PAR between the water surface and substrate level, and gives relatively uniform light over the substrate.


Considering a tank of 24x12x18 inch and 22 gallon, how much CFL and of how much watt would be required??

Thanks in Advance
Jim


----------



## FishAreFriendsNotFood4U

Hoppy said:


> Before any discussion of aquarium lighting can proceed, first we have to debunk the myth about “watts per gallon” being a measurement of light intensity.
> 
> When the only practical source of light for a planted tank was T12 fluorescent tubes, someone decided that the way to pick out the best lighting was to figure out the “watts per gallon” that were needed to grow various types of plants. This would make sense if we could pour a teaspoon of watts of light into a tank, and get a light concentration of X watts per gallon of water, just as we pour a teaspoon of potassium nitrate in the tank to get a nitrate concentration of Y mg per liter of water. But light is nothing like a chemical - you can’t pour it anywhere, you can only shine it on something. That alone should debunk “watts per gallon” as a measure of light intensity.
> 
> But, there is more: Let us assume we have two 20 gallon tanks, with 40 watts of T12 Fluorescent light on each one - 2 watts per gallon. One tank is a 20L and one is a 20H. The 20L tank is 12 inches high, and the 20H tank is 16 inches high. If the fluorescent light sits right on top of each of the tanks, the light on the 20H tank is 4 inches farther from the substrate - 33% farther from the substrate. Because light intensity drops approximately proportional to one divided by the distance from the light squared, the intensity at the substrate in the 20H tank has to be about 56% of that at the substrate in the 20L tank. That alone should debunk “watts per gallon” as a measure of light intensity.
> 
> But, there is more: Let us assume we have two 20H tanks, one with a 40 watt T12 light sitting on top of the tank, and the other with the same light hanging 12 inches above the top of the tank. Again, because light intensity drops approximately proportional to one divided by the distance from the light squared, the intensity at the substrate for the tank with the light hanging 12 inches above the top of the tank must be about 32% of the light intensity of the tank with the light sitting on top of the tank. And, that alone should debunk “watts per gallon” as a measure of light intensity.
> 
> So, that is three strikes against “watts per gallon”.
> 
> But, there is more: Let us assume we have two 20H tanks, one with 40 watts of T5HO light, from a Tek light fixture, the other with 40 watts of T12 light. Anyone who has looked at both a T5HO bulb and a T12 bulb, when they are lit up, knows that the T12 bulb can be stared at without distress, but the T5HO bulb causes some temporary blindness if you look at it for more than a few seconds. The T5HO bulb is much, much brighter, and has to give much more light at a given distance than the T12 bulb.
> 
> “Watts per gallon” is dead!
> 
> 
> 
> 
> 
> 
> 
> 
> 
> 
> *PAR*
> 
> Light intensity can be measured in lux, which is the intensity as perceived by human eyes. Or, it can be measured in PAR units, which is the intensity as perceived by plants. PAR is an acronym for “photosynthetically active radiation” - the radiation (light) that is used by plants for photosynthesis. The units of PAR are micromols of photons per square meter per second. So, a PAR of 1 is one millionth of a mole of photons striking a one square meter area every second.
> 
> Human eyes see the yellow green area of the spectrum of light very well - our eyes are very sensitive to yellows and greens, but we see reds and blues much less well. Plants are very sensitive to reds and blues, absorbing most of the light in those colors, but less sensitive to yellows and greens, reflecting a lot of the light in those colors. That is why most plants look green or yellow.
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> *MEASURING PAR*
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> The best way to find out how much light intensity we have in our planted tanks is to measure it. To do that we must use a PAR meter. A few years ago the only PAR meters available cost a few thousand dollars apiece. Now there are much cheaper PAR meters available.
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> You can buy a Quantum PAR meter, Model MQ, for $329 plus shipping. That is a near laboratory quality meter, with a guaranteed calibration, which can be re-calibrated at the factory when needed. It is the Cadillac of hobbyist PAR meters, usually bought only by clubs, where many members can use it.
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> A lower priced version of the Quantum PAR meter is just the sensor, Model SQ, for $139 plus shipping. To use this you need to either use a good millivoltmeter, which gives the best accuracy, or a cheap lux meter, like the Mastech LX1010BS, from Amazon.com, at about $20 plus shipping. Used with the lux meter you need to do your own calibration. You can use your digital multimeter, with a millivolt scale and the sensor, to determine the PAR from a light at a fixed distance, then connect the Mastech lux meter to the sensor to see what the meter reads at that PAR. This gives you a calibration constant for that combination of sensor and meter to convert lux to PAR.
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> Still cheaper is to buy one of the DIY PAR meters made by Mistergreen and/or O2surplus, for about $60. These are calibrated, and the meter reads in PAR units, but they may not be available when you want to obtain one.
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> Cheapest is to buy a Mastech LX1010BS, at $20 plus shipping, and modify it yourself per Convert Lux meter to PAR meter? but you have to calibrate this yourself. However, the total cost should be $35 or less. If the Quantum PAR meter is the Cadillac of PAR meters, this is the refurbished Volkswagon bug of PAR meters.
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> *SELECTING A LIGHT*
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> Before we can even start to measure the light intensity, or PAR, that a given light will provide on our tank we first have to obtain the light. It may seem that we have to be working blind when we make this selection, given that knowing the “watts per gallon” won’t tell us anything about the intensity we will get. But, because there are now many PAR meters in hobbyist’s hands, we now have a lot of data on how much PAR we can get from several different lights, made by several different manufacturers. More data becomes available every month.
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> Today we can chose one of several different types of lights:
> T5HO fluorescent lights with 1,2,3,4, etc. bulbs
> T5NO fluorescent lights
> T8 fluorescent lights with 1,2,3,4, etc. bulbs
> PC power compact fluorescent lights with 1 or 2 bulbs
> LED lights of many configurations - DIY or ready made
> CFL screw-in fluorescent lights - DIY
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> For each of those types of lights a chart can be made showing the PAR produced by the light versus the distance from the light. These charts show the light intensity as measured without a tank of water being involved - just the intensity as measured in air. This is necessary to avoid the many variations in intensity caused by the tank dimensions and the cleanliness of the tank glass, both of which can have about a 10-20% effect on the intensity.
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> *LOW LIGHT, MEDIUM Light, HIGH LIGHT*
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> I don't believe there is any consensus about the definition of low, medium and high light. But, here is my definiition, subject to, and almost certain to change:
> Low light - 15-30 micromols of PAR - CO2 is not needed, but is helpful to the plants
> Medium light - 35-50 micromols of PAR - CO2 may be needed to avoid too many nuisance algae problems
> High light - more than 50 micromols of PAR - pressurized CO2 is essential to avoid major algae problems
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> The following charts show the data that I now have for various lights. As I get more data I will keep updating the charts and adding new ones. If you want a light that isn’t included in the charts you can study the reflectors used in the light you want and compare them to the photos following the charts to see which charted light is closest to the one you want, to get a rough guess at what PAR that light will give you.
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> Fluorescent tube lights produce about the same light intensity for any length of tube, from about 24 inches to at least 60 inches. The longer bulbs are proportionally higher in wattage, so that the bulb wattage is mostly a measure of the bulb length, not the bulb brightness. For bulbs shorter than 24 inches, this may not be true.
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> *CAUTION: Not all lights use a true, full power HO ballast. Some cheaper models use lower power ballasts, and will not produce as much PAR as those with good ballasts. Compare the chart for the FishNeedIt lights to the others for an example.*
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> One layer of window screen over the bottom half of each bulb, right on the bulb, drops the PAR by about 30%
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> See LED Lighting Compendium for much more information on LED lights.
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> *Photos of various reflectors used in T5 lights:*
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> Hagen GLO 2 bulb light
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> ATI 4 bulb T5HO
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> Home Depot 2 bulb Diamond Plate Shop Light - note the reflections of each bulb.
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> One bulb T8 light with fairly good reflector
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> Aquaticlife 4 bulb Light


Science! Thank you for sharing your knowledge. While I did read your post, I have some questions remaining about my setup specifically that I was hoping you could help with. I understand you gained this info with a 10g tank, so my questions about my 20g are purely theoretical. I have a 20g H, 16 3/4 inches high so I’ll estimate 15 inches from substrate. I’m using a single bulb Sunblaster brand T5HO 39 watt light with a nice reflector over glass. 


















Using your chart I went off the green dashed line “Catalina T5HO one bulb” since that seemed to match with what I have. It seems like the PAR would be 100-60 with no water in the tank, correct? And you said that with water that will decrease the PAR by 10-20% depending on the location in the tank and depth of water. For the chard you used 5 inches of water, so with 15 inches of water in my tank would the PAR be decreased by 20% or more like 3 times that ? Also, would you let me know how much raising my light a few inches would now affect the PAR? 

Again, thanks so much for your post. I feel like I have learned so much more from your single post than reading countless other articles online


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## jeffkrol

Hoppy no longer posts here afaict.
Try Tom Barres barreport.


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