# PAR measurement on a TEKLight-via apogee



## aquanut415 (Jan 21, 2006)

ive got a 48" tek over a 75gallon aga tank sitting on the top rim. the measurements were taken using 2 bulbs in the 2 center slots at 18" below the rim of the tank, where the substrate begins.

Spectralux 6500K - ~60 µmol.m^-2.s^-1 - _previous value was recorded ~40_
Spectralux 3000K - ~90 µmol.m^-2.s^-1 - new data

Philips Master TL5 HO Blue(actinic) - ~50 µmol.m^-2.s^-1 - no change

according to this, actinic bulbs have a similar PAR compared 6500K at 18" below water level.

id like to see other bulb combination PAR stats posted in this thread using 48" teklights.. ive got one more to contribute myself ill get do later

********************************************************
ive redone the measurements, and have to post corrected values. this time i turned of all the lights in the office, and the testing was done at night as opposed to mid day so i think the values are less prone to error. also, for some reason, 1 of the spectralux bulbs took much longer to "warm up" than others so i think that may have contributed to the previously recorded low PAR value for the 6500K lamp. 
In order to eliminate this potential inaccuracy i've allowed all the lights to be run for 10min before i took measurements. ive also retested the prior 2 lamps measurements and repeated for verification. Ive also added a third measurement from a 3000k bulb. please see corrected values above.

all changes made in seagreen


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## Hoppy (Dec 24, 2005)

Hip, hip, hurray!! Some data from the new PAR meters! Thank you very much. One more question: Do these grow low growing plants well? Together or just one of the bubs? That is very interesting about the actinic bulb, and something I kind of suspected we might find. If that holds up for several different actinic bulbs, we should probably start telling folks that those bulbs are just a personal taste issue - if you like it, use it.


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## AndrewH (Dec 24, 2007)

Probably going to find that the low K bulbs (3,000 K to 4,100 K) are gonna have a high PAR reading as well, probably higher the lower the K.

Thanks for posting the findings!!!

Actinic only









Actinic and 10,000 K









Actinic and 3,500 K









The Actinic and 3,500 K don't look too bad together. If it's for the good of the plants, the keeper could definitely find a high PAR mix that they like/can live with.


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## aquanut415 (Jan 21, 2006)

AndrewH said:


> Probably going to find that the low K bulbs (3,000 K to 4,100 K) are gonna have a high PAR reading as well, probably higher the lower the K.


unless im half-asleep, thats the exact opposite conclusion i would make looking at those numbers.


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## aquanut415 (Jan 21, 2006)

Hoppy said:


> Hip, hip, hurray!! Some data from the new PAR meters! Thank you very much. One more question: Do these grow low growing plants well? Together or just one of the bubs? That is very interesting about the actinic bulb, and something I kind of suspected we might find. If that holds up for several different actinic bulbs, we should probably start telling folks that those bulbs are just a personal taste issue - if you like it, use it.


ive never actually used actinic bulbs on an planted tank. im just testing out some bulbs i had lying around. i will say however, i do use actinic lamps to grow emersed plants (an effort to recycle some of the actinic bulbs ive received that came with lamps that i later had to replace with non actinic bulbs) and it works fine on all of them.


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## AndrewH (Dec 24, 2007)

aquanut415 said:


> unless im half-asleep, thats the exact opposite conclusion i would make looking at those numbers.


Plants use specifically the blue and red ends of the spectrum for photosynthesis. Plants tend to like the blue better, but they can use red also.

So red and blue dominate light will have high PAR reading while green and yellow dominate light will have low PAR readings.

My guess is that a tank with a 3,000 K and Actinic light mix will have an extremely high PAR reading and would balance the color enough for the keeper to tolerate looking at it.

Also, a red dominate light will technically have a higher output vs. a blue dominate light due to the extra chems and other stuff they do to get extremely blue light. The extra stuff lowers the light output slightly. Might be 100 lumens different (5,000 vs 4,900), but there will be a difference in favor of the red (which this is aside from their PAR readings which might be very close to the same).


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## aquanut415 (Jan 21, 2006)

AndrewH said:


> Probably going to find that the low K bulbs (3,000 K to 4,100 K) are gonna have a high PAR reading as well, probably higher the lower the K.





AndrewH said:


> So red and blue dominate light will have high PAR reading while green and yellow dominate light will have low PAR readings.


???


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## AndrewH (Dec 24, 2007)

PAR = the measurement of lighting that a plant uses for photosynthesis.

A plant can use the red and blue ends of the light spectrum, which means a light source with a dominate red or blue light would have a high PAR reading. Plants canNOT use yellow and green light as it's simply reflected off the leaves, so yellow and green dominate light will have low PAR readings.

Spectrum values and Kelvin values do not have anything to do with one another.

You can have a low K rated light source (very red) and it still have a high PAR reading (which it should have a high PAR reading).

Did that clear it up?


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## Minsc (Jul 9, 2006)

Interesting data. How old are the bulbs?


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## aquanut415 (Jan 21, 2006)

AndrewH said:


> PAR = the measurement of lighting that a plant uses for photosynthesis.
> 
> A plant can use the red and blue ends of the light spectrum, which means a light source with a dominate red or blue light would have a high PAR reading. Plants canNOT use yellow and green light as it's simply reflected off the leaves, so yellow and green dominate light will have low PAR readings.
> 
> ...


i guess there was no need for that degree in botany i received...:red_mouth
i got what you were saying, but the whole point of the use of the PAR meter is to discuss things quantitatively. lets not bog this thread down with personal opinions.


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## AndrewH (Dec 24, 2007)

Botany and the use of a PAR meter should go hand and hand. Otherwise what's the point of using a PAR meter?


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## bsmith (Jan 8, 2007)

I recently recieved a 36w t5no light with a 10000k and a 420 or 460 actinic. I was actually thinking that the combo of those 2 lights looked very nice for night time viewing.


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## Hoppy (Dec 24, 2005)

My interest in measurements like this is to set up a database of as many lighting types/bulbs, and wattages as we can get, so it will be much easier to pick a suitable lighting setup for whatever tank we are about to start up. Of course it would help to know the PAR reading for each bulb at the centerline, directly under the bulb, at the front and back glass, and at the end of the tank. Eventually so much data would simply get confusing, but back when I was working we had a common statement - no engineer ever had too much data. So, the more this thread is used for reporting PAR meter results, and the less to debating the use of the data, the easier it will be for all of us to use the data as we wish. With that I pledge not to add another comment until I have some data to report - full Boy Scout pledge too!


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## bsmith (Jan 8, 2007)

Dont forget par measurements at specific heights too. :icon_wink



Hoppy said:


> My interest in measurements like this is to set up a database of as many lighting types/bulbs, and wattages as we can get, so it will be much easier to pick a suitable lighting setup for whatever tank we are about to start up. Of course it would help to know the PAR reading for each bulb at the centerline, directly under the bulb, at the front and back glass, and at the end of the tank. Eventually so much data would simply get confusing, but back when I was working we had a common statement - no engineer ever had too much data. So, the more this thread is used for reporting PAR meter results, and the less to debating the use of the data, the easier it will be for all of us to use the data as we wish. With that I pledge not to add another comment until I have some data to report - full Boy Scout pledge too!


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## plantbrain (Dec 15, 2003)

Plants use the entire specturm, not just red and blue light.
You can do a spectral output and also an O2 evolution graph.........assessory pigments can easily nab light in various regions, these include green and yellow light as well, and these pigments are adaptable.

See Lambers, Chapin and Pons text. 

PAR is everything between 400-700nm.
What the heck do you think happens in canopies?
Do you think that only red light is used? Only red and blue light gets through?
What about tannins and turbidity?

Plants need to use every type of light within that range.
That's why we use PAR in the first place:icon_wink

Makes comparing light between systems, treatments etc standard based on growth, flowering etc a standard. There's a lot of different spectra out there, and plants can and do adapt ....so best to measure overall PAR.

This gets around all that monkey business.

Regards, 
Tom Barr


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## plantbrain (Dec 15, 2003)

bsmith782 said:


> I recently recieved a 36w t5no light with a 10000k and a 420 or 460 actinic. I was actually thinking that the combo of those 2 lights looked very nice for night time viewing.


It seems folks have progressively over the years optted to get closer to reef style lighting.

"To yellow" is what many say about 5000K or 6500K even.
I never heard anyone say that 10 years ago.

So trends and preceptions have changed as well, the human cultural side.

Regards, 
Tom Barr


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## bsmith (Jan 8, 2007)

Well ill deff agree with that. Im just glad lightbulb manufacturers are starting to make warmer home bulbs. You should have seen how quickly I was on my way back to Lowe's for some 5000k bulbs after my wife went into the bathroom where I had put 5 new 12w 10,000k bulbs in her vanity!!! :icon_eek: 

I dont remember that choice a few years ago. Almost all fluorescents had that office building feel to them.



plantbrain said:


> It seems folks have progressively over the years optted to get closer to reef style lighting.
> 
> "To yellow" is what many say about 5000K or 6500K even.
> I never heard anyone say that 10 years ago.
> ...


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## defdac (Dec 28, 2003)

> So red and blue dominate light will have high PAR reading while green and yellow dominate light will have low PAR readings.


No, you're talking about PUR.

PAR will be the same for all light (blue, green, yellow, red) between 400-700nm.


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## Left C (Nov 15, 2003)

plantbrain said:


> Plants use the entire spectrum, not just red and blue light.
> You can do a spectral output and also an O2 evolution graph.........accessory pigments can easily nab light in various regions, these include green and yellow light as well, and these pigments are adaptable. ...


This graph shows some of the various pigments used in photosynthesis that Tom is mentioning.


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## aquanut415 (Jan 21, 2006)

update, please see post #1


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## plantbrain (Dec 15, 2003)

aquanut415 said:


> update, please see post #1


Looks about right.
If folks catalog all the bulbs using a meter, then you can make some good predictions, but FL bulbs all wane, tanks are somewhat different, etc etc, which is why using a meter is nice to begin with.

Why spend a lot of time correlating raw bulb data when it's in your tankd ata that is meaningful?

I suppose to compare one bulb to the other...........atinics do work, but look hideous. Sorry, that's my personal choice/opinion there.

I like 5000-8000K, and the GE 9235K are nice as well.

Am I going to buy a bulb based on what I like to see vs a PAR rating?
No, I'll opt for the nice color in most every case.

But for comparing other things, like CO2 demand, uptake etc, 40micromol vs 400 micromol, then I want a meter to measure and adjust things.

For comparing brands and debating "the best" I'm not so sure we can say a lot because of the color preferences folks have. PAR weighs in, but not that much I think............ 

Seems having a moderate to low light for most folks(say 30 to 80) is about best at the tops of the plants for most methods and goals folks have.

That+ a nice color that is pleasing to their eyes.

It's easy to measure all the various bulbs types however. But folks often spend a lot of time trying to do all that and get tunnel vision, not considering the real factors in their tank and their goals, management issues etc 

If you want more light and fast growth, then that's fairly simple, add a MH etc over a small tank or a bank of T5's etc.

But finding a nice balance with the right color seems wise to just use the meter to dial it in then loan the meter out to someone else. You will not need it again until you redo the light or set up another tank etc.

The PAR data for the various bulbs would be nice to have, but it's not going to be the end all result that some think it might be.

Folks get all excited about that, without looking at their individual plants and how things change through time and space etc, how canopies change and how shading influence the growth , reflectors, bulb age, reflectance, rocks/wood, corners, and so on...........

The other thing is the spread of light on the plants for MH's vs T5's or PC's vs T5's etc, small dinky 13 Watt cheapo bulbs vs the nicer 65W PC's etc.

It will be interesting to see now that there are a few meters floating around. Our club just got one for the group to use. While testing is great, the questions asked that you hope to answer are more important than data in and of itself.

Regards, 
Tom Barr


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## plantbrain (Dec 15, 2003)

Left C said:


> This graph shows some of the various pigments used in photosynthesis that Tom is mentioning.


There are other than just these as well.
And those are able to be changed in no# and in location and through filtering within the plant's cells as well. Then the pigments can be increased or shortened to better pick up specific wave lengths. Even if they only get say 50% and not 90% on those peaks, the overall result is still pretty good, it does not have to be the max peak for each peak etc. Each pigment is a "class" that covers a range, not some discrete wavelength.

In marine systems, the depth defines the wavelength to a pretty narrow range, so it's more applicable there(but not as much for macro algae vs corals). For us..........not much.


Regards, 
Tom Barr


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## aquanut415 (Jan 21, 2006)

plantbrain said:


> Why spend a lot of time correlating raw bulb data when it's in your tankd ata that is meaningful?


i just wanted to actually see what the numbers are equivalent too, and get some baseline idea of how much more light i put on my tanks than everyone else. the expense of the meter was negligible to me as i now use it for orchids, aquariums, emersed setups, and to look like a complete nerd at work. :icon_redf
for the most part, i don't plan to change anything im currently doing based on these measurements. things work fine for me even with such high PAR on my tanks.


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## Hoppy (Dec 24, 2005)

The value of the PAR readings for many different types of lighting and bulbs is that it is a starting point for deciding what light will work well with a specific tank before you buy it. Once you have the light, of course you won't be testing it and then discarding it for another one, hoping that one will test better. But, after 6 months, when everyone is telling you you should replace the bulb, you can verify that need by retesting to see how much of the intensity you have lost. Also, with enough data, if you find that the fixture you just spent $200 for gives too much light, you can raise it, retest, readjust the height, and end up with the intensity in the range that you want.

When someone reports and shows pictures of their tank with far less light on it, by wattage, than you "know" is needed, you can look up the probable PAR reading that that person should have, and better understand why the setup works so well for that person.

When a new person asks "what light do I need for my odd shaped 65 gallon tank" you can make a rational recommendation.

And, lastly, I know I violated my solemn boy scout pledge by posting other than data, so I apologize.


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## defdac (Dec 28, 2003)

If you examine the spectral efficiencies of each frequency on Elodea by measuring oxygenoutput you get something like this:









So don't be fooled by pigment-graphs, they don't tell the whole truth. Yes plants can use the all frequencies, but you will obviously get more growth if you focus all electricty on producing blue and red. And perhaps some green-yellow to get pretty light.

This is essentially what triphosors do. Therefore they have nice PUR-efficiency.


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## plantbrain (Dec 15, 2003)

So how much is the RPR?
What rate is it?


While not particular specific to a set of wavelengths or a narrow band filtering:
http://www.apms.org/japm/vol15/v15p29.pdf
The filters where very broad based and are measured and shown, the red and blue did produce the highest rate of growth........

But think about this.............do you want the highest rate of possible growth per watt? Or do you also want a good color for your eye as well?

Is more light better?
Some degree of good efficient watt to light transfer is obviously desired.......and plant to plant species very well may adapt widely, these studies have only been done for a very few species. But.........do we as growers need higher light really?

Probably not.

We want the tank to look nice and to have few algae issues, so efficient ligt is not really what is "best", rather, the moderate to lower light that is good, over a wide range of PAR. We do not know the PUR for every plant species nor can generalize, we simply do not have that information o make that type of conclusion. I'd say in general, yep, it's likely like that, does it matter and are all bulbs that narrow like those filters?

Nope, no even close, so we are back to PAR.
How would you measure PUR with a cheap easy to do rapid method/s for each species and set up??

Seems if you buy into this ...........we all should have red light.
But that, like Atinics, look heidous.
Afterall, the Red band is the most efficient, has the bets dense stem and branching lengths.

Clearly, we must take some trade offs here and lose a small amount of efficency for aesthetics and practical matters, and thus PAR is a good standard, however, no measure is going to be "perfect". It is, however, a long long way from the watts or lumen's measures..........

So we can measure things pretty good over a wide range of various light spectra, even if they are white, red, blue, green slanted.............one way or another.

ADA fixtures and bulbs are fairly "green", however, they still have low PAR. 
This, as ADA claims, reflects the nice green colors of the plants better.
I buy that.

But their low efficiency is really way off..........to the point it makes a large impact on CO2 and nutrients.

All in all, measuring light for our case is not going to be easy, but the PAR meter at least makes a standard that deals with the entire used spectra, even if it's used less in some regions. 

Regards, 
Tom Barr


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## plantbrain (Dec 15, 2003)

Hoppy said:


> When someone reports and shows pictures of their tank with far less light on it, by wattage, than you "know" is needed, you can look up the probable PAR reading that that person should have, and better understand why the setup works so well for that person.
> 
> When a new person asks "what light do I need for my odd shaped 65 gallon tank" you can make a rational recommendation.


Sure, if they also use the same ballast type and brand of bulb and reflector etc. Just the bulb alone is a poor set of data, make sure to detail the other specifics, age of the bulb etc, ballast type.

Now it's starting to be more "work" 
The ADA fixtures had low PAR, but the same bulb on mine had a high PAR, about 2x. So that can make a huge difference.

Regards, 
Tom Barr


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## plantbrain (Dec 15, 2003)

Let's take Haller, Bowes paper on light and hydrilla a step farther and look at their discussion(see link above).

They address the issues effectively,this is really one of those seminal papers, you folks are lucky it is available as an open source:redface: I'm joking, but it really is worth and good honest critical read if any of this stuff matters to you, if not, then you likely should not care enough to bother:thumbsup:

They discuss near the end about Xanophylls, carotenes and adaptative responses. They also mention that there was no significant differences in the growth based on fresh weights, only dry weight, typically we use dry weights in researc to account for water etc, but for aquarist, they use fresh weight biomass(They could dry it and weigh if they wanted to). I believe in dry weights personally for a few good reasons, but it would be hard to tell the difference visually in a person's aquarium.

You will also note that the filters did not entirely eliminate the various other colors, so it's harder to say specifics about the light. Issues like this come up all the time, however many will overlook these other discussions and not include them in the references. They are important and part of the paper and conclusions.

Like low light? Then this is a good paper about that:
http://www.apms.org/japm/vol15/v15p32.pdf

Also freely available open source.
No method will be perfect and such issues are accounted for.
There are going to be trade offs with anything. Knowing what they are and looking at the assumptions and accepting the best for the application is about all you can do. At some point, someone very clever might change everything, but I do not see that happening here for a long time.


Regards, 
Tom Barr


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## Hoppy (Dec 24, 2005)

plantbrain said:


> Sure, if they also use the same ballast type and brand of bulb and reflector etc. Just the bulb alone is a poor set of data, make sure to detail the other specifics, age of the bulb etc, ballast type.
> 
> Now it's starting to be more "work"
> The ADA fixtures had low PAR, but the same bulb on mine had a high PAR, about 2x. So that can make a huge difference.
> ...


Well, @$#^%&(#%@


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## helgymatt (Dec 7, 2007)

Hoppy said:


> Well, @$#^%&(#%@


LOL....some things just are never simple. I agree with Tom that there are so many variables that having a database would be really tough for all the tank sizes, bulb types, reflectors, hight of fixture water, etc....

Having access to a PAR meter is proabably the only real good solution. Hopefully they just continue to get cheaper:thumbsup:


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## defdac (Dec 28, 2003)

plantbrain said:


> But think about this.............do you want the highest rate of possible growth per watt? Or do you also want a good color for your eye as well?


I certainly want the highest possible growth rate per watt and good color as well. Triphosphors is good in that way - they produce the highest amount of PUR and still they manage to produce sufficiently nice color output.



> Is more light better?
> Some degree of good efficient watt to light transfer is obviously desired.......and plant to plant species very well may adapt widely, these studies have only been done for a very few species. But.........do we as growers need higher light really


Here it really shows we come from totally different parts of the world. You from the APD/USA where folks generally tend to overdo and insanly overshoot the requirements by far, and I from Sweden where folks generally only have the lighting that is shipped with the cheapest setups they can find.

In your view more light is certainly not better, but from my point of view it's totally necessary.

You like to generalize to be able to give good advice that is good for most people, but here you cannot.



> We do not know the PUR for every plant species nor can generalize, we simply do not have that information o make that type of conclusion. I'd say in general, yep, it's likely like that, does it matter and are all bulbs that narrow like those filters?


You don't want to generalize when it suits your argument. But here is a place where you CAN generalize. Heck - look at the photosynthesis action spectrum for zooxantheallea - is it really much different from that of an Elodea. Nope.

So you actually CAN calculate PUR to a very close approximation for most plants.



> Nope, no even close, so we are back to PAR.


Wrong. Very close, and you have the PAR-value for free. Then you see the PAR-value does not change for much for each bulb.

Why is that?

Because all bulbs have similar output between 400-700nm - but how much blue and red is radically different, and that does show for the PUR-measure and it's a very close approximation. A good generalization.



> How would you measure PUR with a cheap easy to do rapid method/s for each species and set up??


You don't have to. If you know the spectral distribution and Lux it's all you need to calculate both PAR and PUR. That is why I will show with my Apogee-meter.

That is math magic right there, and those who get it will drop their jaws.

The basics is that if you know how much Lux is produced you know how much photons is falling inside of the photooptic curve. You also know how much wattage it took to get the Lux-measure that produced the amount of photons. You can then calculate how much photons is falling outside of the photooptic curve, for example inbetween 400-700nm.. That is PAR right there.

With the spectral distribution and a generalized action spectrum you then with some more math knows how much usable radiation you get. That measure radically differs for different bulbs. PAR does not.


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## Jens (Apr 21, 2006)

defdac said:


> _Triphosphors_


a marketing term heavily use in Europe for plant lightning. Didn't seem to fly in the USA as such. Still most bulbs are from the handful of European manufactures. We do play with the same stuff.


defdac said:


> *cheapest setups*


Ain't the best approach either. And afterward starting to chase the best bulb base on scientific methods isn't the most effective way either. And what is the final result, 5% maybe 10% increase in growth? If you use a good fixture and lightning source you can have a increase of whatever without increasing the actual watt or even using less watts. Now the PAR measurement discussion is actually to prove an idea on how much light is good enough and which lightning solution will be the most effective and environment friendly solution in the end and not about chasing the last bit of usable photons. It'll be much easier to do this with the American Way of overshooting everything. Not the goal here! PAR values will give everybody an idea about the light quality and quantity without being to concerned about the underlying scientific principles of photosynthesis. As said, lightning color is a very personal choice as well which has to be balanced with PAR/PUR anyway. 


defdac said:


> That is math magic right there, and those who get it will drop their jaws.


And this is the European way of over-analyzing everything with little practical value in the end. Put up something on a website to get same general use for the public out of it instead of bathing yourself in your intellectual ego. Make sure to add sufficient supporting documentation to prove your point! Wait a second, that could get a little expensive


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## Hoppy (Dec 24, 2005)

I think there is a lot of value in both approaches. If I am just starting out in this hobby, and want to grow a certain selection of plants, I will want to know what light fixture/bulbs to buy that will let me do that, but not overshoot so far that my new hobby will end up making me nothing more than an algae fighter. For that I think the PAR measurements will be extremely useful.

But, eventually I will want to know more about how plants grow and why certain parameters affect the growth. Part of learning that is to learn more about photosynthesis, and how light affects it.

A lot of this seems to me to depend on what goals you are trying to achieve. I know that Defdac is very much interested in light spectra and plant growth, and that has led him to do a lot more research into that field, plus a lot more testing than most of us are interested in doing. He has my thanks for doing that.


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## plantbrain (Dec 15, 2003)

defdac said:


> I certainly want the highest possible growth rate per watt and good color as well. Triphosphors is good in that way - they produce the highest amount of PUR and still they manage to produce sufficiently nice color output.


I'm less concerned about this, a little, but color temp and PAR are what I use for comparisions between light output, not PUR. Using bulb data is nice and all, provided they give it and it is accurate and ...........does the PUR stay the same over the life of the bulb or does it change?
I do not know, but I'd say it does change.........How do you account for that?
Can you measure this?

It'd be nice to have such data for each plant species after it has adapted well to a particular light and you looked at all the relative rates of growth, but that is not the case near as I can tell. The studies I've read showed some significant differences with Green Vs Red light and Blue, but none in the fresh weights.

These where 2 week growth studies.
I've used spinach leave chloroplast and do a similar lab for students showing how the action spetra works using filters, but these are measured with a PAR meter to maintain the same intensity(since we know the filtering). You are not going to find PUR meters for the hobby, you will find PAR meters at a reasonable cost.

So these are the most practical given the wide range if light types availble wolrd wide and with respect to sunlight(which color temps change throughout the day).



> Here it really shows we come from totally different parts of the world. You from the APD/USA where folks generally tend to overdo and insanly overshoot the requirements by far, and I from Sweden where folks generally only have the lighting that is shipped with the cheapest setups they can find.


Huh?
Where's this one come from? I do agree, _Ikea_ is cheap stuff:redface:
Okay, I still like the stuff. haha
In any research approaches, you use a control say no nutrients, and another than is non limiting to see your upper and lower bounds, the environment that you are interested is general equal to or somewhere in between.

If you do not explore the upper and lower bounds, you do not learn as much.
This is not a cultural issue, this experimental and any good research will address these two extremes, regardless of culture, that does not even factor into why I do this.



> In your view more light is certainly not better,


Now we are getting into semantics........it depends on what goal I or someone might have Andrew here likes very high light, for him it is better......in other cases, I have strongly promoted the use of lower light, much lower than what many have long assumed we could get away with, and I've done so based on observation and examples for a very long time. Will this PUR help? I think you'll be strong pressed to show that for aquarist, it will make a significant difference.



> but from my point of view it's totally necessary.


Then show that it is (for your goal), show two bulbs types, one that does have a nice U shape action spectra and another that an aquarist might buy that does not have good characters, mostly Green and yellow etc. Grow several sets of replicates over time and give them severla weeks of trimming and time to adapt, then dry them and weigh the rates of growth.

Chose one species, then use another or a set of several for eachg replicate.



> You like to generalize to be able to give good advice that is good for most people, but here you cannot.


About what specifically?



> You don't want to generalize when it suits your argument. But here is a place where you CAN generalize. Heck - look at the photosynthesis action spectrum for zooxantheallea - is it really much different from that of an Elodea. Nope.
> 
> So you actually CAN calculate PUR to a very close approximation for most plants.


I guess using the data from the bulbs, but that data changes as we use the bulbs/they age. They do not provide that data. Many bulbs already have the same/similar type of action spectra and even if they do not, it's not like that are missing all of the red or blue either. Given that and the fact we do not use just narrow range Green 555 nm bulbs..............PAR works pretty well.

Even where filtering does occur, under a controlled study using Hydrilla, the researchers did not find significant differences with Fresh weights of the plants, only with dry weights.

So when you factor in the practical horticulure and various light bulb brands and electronic ballastic, mangnetic etc, reflector aspects, you are back to PAR anyway.

If you really care that much about squeezing every bit out of that light, significant or not........ bully for you. I look at each side, practical aspects etc and then make a suggestion based on that. 



> Wrong. Very close, and you have the PAR-value for free. Then you see the PAR-value does not change for much for each bulb.


What? Do you realize what you just said here?
Bulbs are NOT the only aspect here, ballast, reflectors, tank distance from the bulb, depth of the tank, location location location within the tank, the front of the tank, the back, slightly shadowed by the wood etc.

You think using PUR data provided by the makers of bulbs is going to be better, best relative to actually _in situ_ measurements that do account for all the variations? Theory vs field measurements???.........don't get me started.

If we used your apporach, then ADA light intensity would still be the same as my Coralife hood:icon_eek:



> Because all bulbs have similar output between 400-700nm - but how much blue and red is radically different, and that does show for the PUR-measure and it's a very close approximation. A good generalization.


I agree with that, but using it as a general guide with PAR readings, I'll defer to the PAR readings in each case however measured in situ.

There was a study done comparing relative growth rates using cool whites and pricy plant bulbs and they found no significant differences. They look bad in the tank, but as far as growth, they do no better.

Unless you get a rather weird bulb, it will be hard to show a significant difference in growth for the Triphos bulbs vs cool whites or others.
That is the data and the results we have. You are not going to get around that without showing some really convincing research showing otherwise. 

You say that the PUR is very different and if so, we should also see large differences in the relative rates of growth, but with typical bulbs, not narrow 10nm wavelength bulbs/filters etc, we do not have such evidence.

Maybe you think that you can use the PUR data spectra to find more than is there in practical terms?:thumbsup:



> You don't have to. If you know the spectral distribution and Lux it's all you need to calculate both PAR and PUR. That is why I will show with my Apogee-meter.


Okay, that's fine, I buy that.
But to what end.......?
Will it be of use in situ and accunt for these other issues like ballast, reflectors etc etc etc............you know...reality in the tank?

That's where the PAR meter comes in handy and why botanist use them.
They have measured the sun over the full day cycle, but even that changes depending on the time of year, dust in the air, fog, water vapor, smog, wind, etc.



> That is math magic right there, and those who get it will drop their jaws.


I'm not into magic, I'm more into comparing each tank and bulb/light system on an euqal footing. We do not have narrow band filters, we do not all have the same plant species, same distances, same ballast.

What might be the same PUR value for you, might be different for ADA, or Coralife, or Bubba's tank. I welcome the idea, I'm just not seeing the real value without addressing the other issues.

Maybe I'm just bone headed:redface:



> The basics is that if you know how much Lux is produced you know how much photons is falling inside of the photooptic curve. You also know how much wattage it took to get the Lux-measure that produced the amount of photons. You can then calculate how much photons is falling outside of the photooptic curve, for example inbetween 400-700nm.. That is PAR right there.
> 
> With the spectral distribution and a generalized action spectrum you then with some more math knows how much usable radiation you get. That measure radically differs for different bulbs. PAR does not.


You'd need to integrate that radiation, that will be tough in the real world. That's why I asked if you have a PUR meter, the method you suggest will not nswer your question, it will only give an approximation, is it better than PAR? I do not buy it, certainly not with all the other field issues vs a theorectical model, which leads you back to a PAR meter. No method for light is perfect.

I think comparing PAR and PUR is not bad in anyway and maybe you could argue a little more PUR in one bulb type will offer you a bit less lighting cost, or more usable plant light in lower light situations. At higher light, will not matter much however, the rest are aesthetical values of the aquarist once you get above a critical LCP.

But most of the gains there for efficiency have been with MH's, PC's, E ballast etc now T5's, nice mirrored reflectors etc, not focusing PUR values that are better for plants near as I can tell. 

So you could argue using PAR(in situ) and PUR data(theory modeling) to chose the best bulb for you. I think that is your point here?
I buy that. Whether it is significant in the real world is quite another matter, that has not been shown.

I need more convincing.

Regards, 
Tom Barr


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## plantbrain (Dec 15, 2003)

Jens said:


> Make sure to add sufficient supporting documentation to prove your point! Wait a second, that could get a little expensive


No, I think a common sense approach and looking at what we do as horticulturalist is a good method, take a step back and ask" what is it that we are comparing here?"

Bulbs.........Andrew started with this topic.
PAR was pretty close.
Blue light alone will do pretty well with Hydrilla and I'd suspect Elodea with rates of growth.

There is such evidence.

But we generally use wide broad spetrum light bulbs that have good blue and red mixes as well as green and yellow mixed in.

We also need something more than theory to confirm and verify light in situ, we need to measure in each tank to keep the light the same.

You can use the PUR data(theory) and then go back and make sure the PAR is within relatively similar ranges in any ype of set up. The PAR is good for that. Most folks like the nice color appearances, so that's a large fator also.

So Color for aesthetics, PUR for the best bulb efficiency theory, and PAR for in situ measurements.

That seems fine to me. So PAR works fine for what we are using it for. PUR is not measured in situ, we can measure Lux or radiometric(W/m^2 etc) but most all plant science folk use PAR to make things standard for comparative purposes.

It's a can of worms really, but that's what is used.

Regards, 
Tom Barr



Regards, 
Tom Barr


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## defdac (Dec 28, 2003)

Jens said:


> a marketing term heavily use in Europe for plant lightning. Didn't seem to fly in the USA as such. Still most bulbs are from the handful of European manufactures. We do play with the same stuff.


Marketing aside, there are alot of triphosphors and they are easy to find just by looking at the spectrum. They seem to give alot of punch for the buck because they focus their energy on three wavelengths.



> Ain't the best approach either. And afterward starting to chase the best bulb base on scientific methods isn't the most effective way either. And what is the final result, 5% maybe 10% increase in growth?


Perhaps, or maybe a little more. Still the reflector choice is the best bet for getting more light.



> And this is the European way of over-analyzing everything with little practical value in the end. Put up something on a website to get same general use for the public out of it instead of bathing yourself in your intellectual ego. Make sure to add sufficient supporting documentation to prove your point! Wait a second, that could get a little expensive


http://82.183.138.227/GTKTest/GTKTest.html
You're welcome. =)


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## defdac (Dec 28, 2003)

plantbrain said:


> I'm less concerned about this, a little, but color temp and PAR are what I use for comparisions between light output, not PUR. Using bulb data is nice and all, provided they give it and it is accurate and ...........does the PUR stay the same over the life of the bulb or does it change?
> I do not know, but I'd say it does change.........How do you account for that?
> Can you measure this?


They do change, but not nearly as much as they get totally different outputs on the three main wavelengths that gives the punch.

I've also measured three year old triphosphors (those with three distinct peaks in their spectrum at blue, green and red) and they actually only drop 10% intensity over their life span. No marketing hype there. It is actually true. 

Use them until they fail. Economy right there.



> It'd be nice to have such data for each plant species after it has adapted well to a particular light and you looked at all the relative rates of growth, but that is not the case near as I can tell. The studies I've read showed some significant differences with Green Vs Red light and Blue, but none in the fresh weights.


So they can adapt do crappy light that they reflect (green/yellow). Can they adapt to intense blue and red that is more efficient to use? Ofcourse they can.

Why go for bicarbonate when you get CO2?

Easy choice.




> Huh?
> Where's this one come from? I do agree, _Ikea_ is cheap stuff:redface:
> Okay, I still like the stuff. haha


You know I'm your biggest fan of all time in this hobby, still. You need something to take a bite at sometimes 
EDIT: Totally embarrising fault corrected in that sentence, I'm so sorry :icon_redf



> Now we are getting into semantics........it depends on what goal I or someone might have Andrew here likes very high light, for him it is better......in other cases, I have strongly promoted the use of lower light, much lower than what many have long assumed we could get away with, and I've done so based on observation and examples for a very long time. Will this PUR help? I think you'll be strong pressed to show that for aquarist, it will make a significant difference.


For someone that already have 4 watts/gallon - no need at all.

For those not having the wattages but want to optimze. Sure.



> I guess using the data from the bulbs, but that data changes as we use the bulbs/they age. They do not provide that data. Many bulbs already have the same/similar type of action spectra and even if they do not, it's not like that are missing all of the red or blue either. Given that and the fact we do not use just narrow range Green 555 nm bulbs..............PAR works pretty well.


You will get high PAR with a bulb shooting only green. Food for thought.



> If you really care that much about squeezing every bit out of that light, significant or not........ bully for you. I look at each side, practical aspects etc and then make a suggestion based on that.


Yeah. Buy a big block V8 and get beaten by a small Lotus Exige.

Be smart. I certainly know you are. I try to be.



> What? Do you realize what you just said here?
> Bulbs are NOT the only aspect here, ballast, reflectors, tank distance from the bulb, depth of the tank, location location location within the tank, the front of the tank, the back, slightly shadowed by the wood etc.
> 
> You think using PUR data provided by the makers of bulbs is going to be better, best relative to actually _in situ_ measurements that do account for all the variations? Theory vs field measurements???.........don't get me started.


Still. Don't shadow the plants, pick a good reflector and electronic ballast.

And choose a good bulb with a high PUR-efficiency. 

Why should you pick a crappy bulb when you can select one that really hits hard where it counts?

We have the data, heck I even give it out for free. =)



> You'd need to integrate that radiation, that will be tough in the real world. That's why I asked if you have a PUR meter, the method you suggest will not nswer your question, it will only give an approximation, is it better than PAR?


If green bulbs give high PAR, what use does it have? Sure you can use them if you want to waste electricity.


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## Jens (Apr 21, 2006)

defdac said:


> http://82.183.138.227/GTKTest/GTKTest.html


Nice little gwt app! Thanks

How does the mapping of the spectrum work? What kind of images does it take?

Which formulas is it using ?


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## defdac (Dec 28, 2003)

Jens said:


> How does the mapping of the spectrum work?


It iterates from top to bottom each column of pixels until it reaches a black pixel. Each pixel colum = 1 nm.



> What kind of images does it take?


Black and white any size jpg/gif. Use photoshop or similar to convert to black & white and also use the posterize function to make the picture pure black & white and not grayscale.



> Which formulas is it using ?


Ivo Buskos from his great article here:
http://www.aquabotanic.com/lightcompare.htm

I only made the picture->data converter with JAI to make it a bit more usable. Still the GUI needs some serious work and I never can find the time to make it better.

But I have made a spectrum->kelvin algorithm and will be able to show the attenuation in color depending on depth. The attenuation will be based on a user uploaded attenuation distribution instead of just one Kd-value on all frequencies.


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## macclellan (Dec 22, 2006)

Here's a bunch more data. 
All measurements in ~60 µmol.m^-2.s^-1
Taken with an Apogee QMSS-E PAR meter.
All values are approximate.
_Please don't quote this post in its entirety for you will look retarded._

*14g Ecosystem Aquariums “Mini” AIO. Reef Tank.*
Wal-mart 500w Halogen Worklight for housing, end-caps, reflector, wiring, etc. 70w Icecap ballast.
70w Catalina Aquariums “Coral Grow” 14KK
70w (5 "WPG" but more like 6 "WPG" in display area, ~12g)

Surface (10”): 310
15” middle: 140
21” middle: 100
21” front corner: 150 (due to shape of reflector?)
21” rear corner: 100

*Standard AGA 75g Aquarium. Freshwater planted.*
Catalina Aquariums T5 Fixture w/Workhorse Ballasts. 
2x54w 67KK and 2x 10kk stock Catalina bulbs, approx 4 months old.
Bottom of the bulb plane is 2” off of surface with legs.
216w total (2.88 “WPG”)

With dirty glass top: --- Open top --- Cleaned glass top
Surface (2”): 450 --- 550 --- 480
15” middle 120 --- 145 --- -
21” middle 65 --- 90 --- 80
21” front 40 --- 80 --- 70

*Standard AGA 30L. Freshwater planted.*
AHSupply PC reflector retrofitted in a AGA striplight, Workhorse 5 ballast.
96w 67KK bulb…whatever brand AHSupply uses, approx 18 months old…sigh.
Reasonably clean glass top between bulb and tank.
96w (3.2 “WPG”)

Surface (1”): 350
16” middle: 55
16” front: 50
16” Front corner on endcap side: 5
16” Front corner on non-endcap side: 15
16” Back corner on endcap side: 30
16” Back corner on non-endcap side 40

*Same measurements, but now with a 30” Coralife T5-NO added over the front of tank*.
1x18w 67kk and 1x10kk stock bulbs, approx 8 months old.
132w total (4.4 “WPG”)

Surface (1”): - 
16” middle: 75
16” front: 125

*Standard AGA 10g. Freshwater planted.*
AHSupply PC reflector retrofitted in a AGA striplight, Workhorse 3 ballast.
36w 67KK bulb…whatever brand AHSupply uses, approx 24 months old…sigh.
Reasonably clean glass top between bulb and tank.
36w (3.6 “WPG”)

Surface (1”): 350
6”: 115
11” middle: 100
11” middle front: 65
11” Front corner on endcap side: 30
11” Front corner on non-endcap side: 45

*Standard AGA 10g. Low tech planted.*
Ghetto Wal-mart Incandescent hood. 
Custom-made (by yours truly) quasi-parabolic polished aluminum reflectors.
2x10w Wal-mart PC fluorescent bulbs (non-spiral).
No top, but quite dirty plastic bulb shields.
20w (2 “WPG”)

Surface (2”): 200
12” middle: 35
12” front center: 25

Observations (What I learned or had reinforced through taking these measurements):
Clean glass tops are really important for more light getting to photosynthetic life. Much more so than I would have thought.
The endcap side versus nonendcap side of PC lights makes for a much larger difference in light than I would have thought. This does not happen with T-5 and is a huge advantage over PC.
It seems that even T5-NO with the crappy Coralife reflector is brighter than AHS PC. This is inconclusive though. I wish I had taken measurements with just the Coralife on and the AHS fixture off. Also, I need new PC bulbs.
Comparing the 10g tanks, my ghetto-lit tank is brighter than one would think and has better spread compared to an AHS-PC lit tank.


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## plantbrain (Dec 15, 2003)

defdac said:


> They do change, but not nearly as much as they get totally different outputs on the three main wavelengths that gives the punch.
> 
> I've also measured three year old triphosphors (those with three distinct peaks in their spectrum at blue, green and red) and they actually only drop 10% intensity over their life span. No marketing hype there. It is actually true.
> 
> Use them until they fail. Economy right there.


I said this over 10 years ago with respect to PC bulbs, got poo pooed for it too

So do the main spikes drop, or just the overall output, or is it even across the spectrum?
That is a more specific question I am asking, not economy, I already know T5's and PC last and last till they die and I'm on record having stated that going way back.



> So they can adapt do crappy light that they reflect (green/yellow). Can they adapt to intense blue and red that is more efficient to use? Ofcourse they can.
> 
> Why go for bicarbonate when you get CO2?
> 
> Easy choice.


Hold on there. Are cool whites really that bad?
Which crappy bulbs are talking about here?
Be specific.

Unlike Bicarb vs CO2, with these changes in light, you DO NOT get a 2000% increase in growth rates in submersed plants.

That I can promise you. 
What say you to the study that showed the same rates of growth for the pricy bulbs vs the cool whites? I saw the actual paper some years ago, but since have not been able to locate it. But it was no differences in the rate of growth. 

Where are cool white bulbs on the calculator?



> You know I'm your biggest fan of all time in this hobby, still. You need something to take a bite at sometimes
> EDIT: Totally embarrising fault corrected in that sentence, I'm so sorry :icon_redf


I'm all for that. Any feedback is good. And boy, my Ikea desk works nicely, hehe.

No, I prefer some good debate about this, some practical citations also help.
Calculators and effiencies yada yada...........that's nice when modeling........and models can be important..but I look at the real systems, the field, the aquarium itself etc.

That's where I like to start and measure, then see if the model matches what we see in the field, then adjust the model better etc.

Often times you need to test in your specific tank to make adjustments to a model, it's not to be used as a sledge hammer.

No model is, this light model is no exception either.



> For someone that already have 4 watts/gallon - no need at all.
> 
> For those not having the wattages but want to optimze. Sure.


No, I do not think you need to go that high at all, 2 W/gal works just fine, name one bulb where I'll see a large difrference I can measure?

I used several bulbs and used cool whites and could not for about 6 years.
That's not at 4 w.gal, that's a fair amount less(80 micromols). A T5 light with 1.5 W/gal had 120 micromol at the same distance, that is significant and you can measure that in growth rates.

Even with control test using specific filters and equal micromol PAR, Bowes and Haller did not fine that much statistical difference and none with fresh weights. Our lights are not that far off from each other.

Nothing like the filters used in those test.

So it's questionable what you are claiming here about growth and getting everyt last bit out of it. You have not shown this in the results.
And research suggest it's not that big a difference even under ideal circumstances.

You have not proved your case that you really do get more out of the light to the point it makes a differences in terms of growth.

You have to demonstrate it or show some research that has. Otherwise I do not buy it. Otherwise you are asking me to take it on faith or theory. That's an assumption and not the safe type.



> You will get high PAR with a bulb shooting only green. Food for thought.


Yes, but no one uses narrow band green bulbs in the hobby(do you know anyone?), even cheapo cool whites and daylights are not narrow green and even the study I cited shows even under the worse cases, there was some significant differences, but not a lot.

This is hyperbole arguing here, not citations nor field measures, name such a bulb and let's see it's action spectrum? Not many use atinics because they are narrow range and look hideous, Marine do but for other reasons. 

The PUR range is nice as model, but I just do not see it really being that big a difference to you or anyone else.

I'm not convinced and nothing presented has supported your claim, I need to see something that says you get more growth out of one bulb vs another based on a few units of PUR.

You have not demonstrated that.
If you want to make the case that it does, then you need to demonstrate it.

That's what this boils down to.
PAR is the best I have, dry weights, fresh weights etc.
I can model etc, but if I have nothing to back up the model using PUR that shows it is significant, I have no leg to stand on.



> Yeah. Buy a big block V8 and get beaten by a small Lotus Exige.


Are you being Smug? haha
A T12 with a magnetic ballast vs an electronic ballast and T5.
Same spectrum, but a large difference in output and growth rates.
Few would argue that.

So where is the example of a poor PUR bulb that is commonly used in the hobby?



> Still. Don't shadow the plants, pick a good reflector and electronic ballast.
> 
> And choose a good bulb with a high PUR-efficiency.
> 
> ...


I like shawdoing the plants like Anubias, and want to know how much light they are getting and is it enough. Other species look nice in the brighter regions in the canpoy etc. 

Your advice to not shawdow, use reflectors, and E ballast, and we may as well add use T5's are the lion's share of the pie here, the PUR part is small potatos.

Which is what I've said all along, you have to show there's a difference, relative rates of growth, O2 production, something. Back ground research support etc. I have nothing but a theoretical model, your word and belief.

I have not seen a difference in practical observations and I've used less light in many tanks over the years and espoused the use of lower light for Everything from Gloss, to HC and hair grass etc, all of which folks have long claimed are high light plants requiring 3-4 w/gal.

PUR is not what saved me when I used low light. I used many different bulbs.

E ballast, reflectors, T5 vs T12 and T8 vs T12's etc, spread of the light angles etc.

Those are what we can see are the lion's share of the improvements and there's evidence that supports that. 

I'm still not convinced that PUR is really that significant based on the commonly used bulbs. T5's, PC's and HQI's are the more common bulbs used here in the USA lately. A few still use T12's and more use T8's, but many seem to get the better e ballast, reflectors, and more efficient bulb types in general, which have a higher PAR reading. More PAR = more growth in most cases unless it's a narrow band and all green etc vs Red or Blue and even then, not that much.

Try searching for some support, references etc, something with RGR's and plant growth rates etc specific for this. 

Regards, 
Tom Barr


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## defdac (Dec 28, 2003)

plantbrain said:


> Your advice to not shawdow, use reflectors, and E ballast, and we may as well add use T5's are the lion's share of the pie here, the PUR part is small potatos.


Yepp, it's kindof small potatos I agree to that. Kindof average sized anyway. Reflectors is where you really make the difference. All T5:s have electronic ballasts so nothing much to do there.



> Hold on there. Are cool whites really that bad?


Absolutely not, and that is perhaps where the PUR-efficiency measure helps the most: To get a measure for what kind of bulbs are really bad and which ones works good. Most bulbs sold today is tri-phosphors and are really efficient. So the measure proves your point perfectly.

But from the worst Halogen-bulb to the best T5 tube there is a factor five in efficiency. That's not that small potatoes I think. Rather big ones.

If you would compare the PAR-measure between the worst Halogen bulb to the best T5-bulb the same factor is only two. 

It's good to understand that a high Lux bulb will also have high PAR, but not high PUR. That means if you measure high PAR under yellow light with high Lux you will be fooled and think you have strong light for the plants, when it probably will only be average for the plants and thus wasteful. 

It's also interesting to see bulbs specifically made to have high PUR (much blue and red light) have rather poor PUR-efficiency. GroLux, Fluora and such. These bulbs have a very odd phosphor-mix which turns out to give rather poor intensity, and then it's not much use to all the blue and red they produce.


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## plantbrain (Dec 15, 2003)

Let's take this debate off this thread and start another. 

Regards, 
Tom Barr


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## youareafever (Mar 18, 2008)

any more measurements out there?


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