# Why manufacturers don't post PAR read ever? (or ONF lighting problem))



## EdWiser (Jul 14, 2015)

Many factors is measuring PAR. I have been measuring par on club members tanks for 20 years now. You just can not print out a Par chart on a light as there are factors like depth of tank water movement, spectrum. It’s always best to have an adjustable light. Many freshwater lights are just on/off. You can rent PAR meters if you do not have a local aquarium club that has a PAR meter. 

https://aquarium.bulkreefsupply.com/reefing/Par-Meter-Rental

If you don’t want to do this just turn down the light to Half and watch the tank for a month an see how the plants react.


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## Anon (Mar 16, 2014)

Hi Ed,

You and I communicated elsewhere just a few days ago.

I am delighted to have discovered your post above. Aquarium lighting is of particular interest to me. Will be asking more about PAR measurement a little later today.

Anon


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## EdWiser (Jul 14, 2015)

I am on many forums. An a mod on many too. [emoji3] love talking and sharing thoughts. I started test par because it was something I had to do in the real world at product inspection stations at work once a month. [emoji3]


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## Anon (Mar 16, 2014)

EdWiser said:


> I am on many forums. An a mod on many too. [emoji3] love talking and sharing thoughts. I started test par because it was something I had to do in the real world at product inspection stations at work once a month. [emoji3]


Hi Ed,

Me again!

I have been frustrated a long time for not being able to reliably measure PAR. Recently, I identified the Apogee SQ-520 as a candidate. I chose this over some of the other Apogee PAR sensors as it covers the entire spectrum from 400nm to 700nm. I also like the idea of plugging it into a PC USB socket and using the Apogee software. Do you have any experience of this product?

Anon


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## jeffkrol (Jun 5, 2013)

Anon said:


> Hi Ed,
> 
> Me again!
> 
> ...


No experience personally but as far as quantum sensors go.. it's like "the go to" one...
Seneye "works" fine from most practical experiences but it's just not as err accurate .. as you saw since you looked at response spectrums..


currently about $100 difference between the really only 2 models (though the Apogee 200-ish uses a similar response sensor)

https://premiumaquatics.com/product...MIkoyr8aLW5gIVR_fjBx0dOAmREAkYASABEgJRj_D_BwE


Bulk reef supply may have it on sale as well


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## Ddrizzle (Jan 30, 2019)

Anon said:


> EdWiser said:
> 
> 
> > I am on many forums. An a mod on many too. [emoji3] love talking and sharing thoughts. I started test par because it was something I had to do in the real world at product inspection stations at work once a month. [emoji3]
> ...


I have this and it's as straight forward as you can imagine as long as you have a laptop around.

But buying the par meter is the easy part. The hard part is being able to test any light you desire.


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## Anon (Mar 16, 2014)

jeffkrol said:


> No experience personally but as far as quantum sensors go.. it's like "the go to" one...
> Seneye "works" fine from most practical experiences but it's just not as err accurate .. as you saw since you looked at response spectrums..
> 
> 
> ...


Hi jeffkrol,

Thanks for your reply.

I used to have a Seneye. Never again. When you say "as you saw since you looked at response spectrums..", I'm confused. How did you know that I had looked at response spectrums? I must have mentioned this somewhere, I guess. Oh dear, my brain is seizing up - yet again!

I take it that the SQ-520 is a good choice?

Anon


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## Maryland Guppy (Dec 6, 2014)

One would think by now that a PAR rating would be printed on any box that contained a light.
It could be an open air reading @ maximum intensity with say 6" increments.
At least this would put people in the ballpark.

And they label things for planted tanks!:grin2:


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## Freemananana (Jan 2, 2015)

While it would be nice to get an idea, you can rough estimate based on wattage still. It's an old and out dated method, but you do get an idea of the output of the light. The biggest thing is researching similar tank sizes and see what people are running as far as the depth goes. I originally struggled with too weak of a light before I realized that the depth is what cuts down on the strength of the source.

Your light is 4500 lumens, which again is an old and dated measurement, but that should give you an idea. On my last 20g tank, I ran a beamswork LED which was 1200 lumens. It was just under 14w of power as well, with 0.5w leds. I was in the low light territory but had no problem growing dwarf sag, floatings, guppy grass, anubias, etc. You could cut your light to less than half if you are running without CO2 and likely have no issue with a decent length day schedule.


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## jeffkrol (Jun 5, 2013)

Anon said:


> Hi jeffkrol,
> 
> Thanks for your reply.
> 
> ...



I regret the day I picked the Seneye over the 520............
Not that the Seneye was bad...
it def. isn't.


I can only boil it down to sort of a personal choice..


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## EdWiser (Jul 14, 2015)

Anon said:


> Hi Ed,
> 
> 
> 
> ...




Yes that one is great I used a meter that logged the reading for me. As I had paper work to fill in for PM. 
You can use this model or just get the meter model. For hobby use the software version would be useful if you are doing checks of light on many tanks or greenhouse.


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## EdWiser (Jul 14, 2015)

Maryland Guppy said:


> One would think by now that a PAR rating would be printed on any box that contained a light.
> 
> It could be an open air reading @ maximum intensity with say 6" increments.
> 
> ...




The problem is water. [emoji3] Water can really mess with light. Water can cut the Par by 3/4 at the bottom of a tank. Also at an angle par can drop off fast. The human eye is terrible at determining how much light puts out as we have a small spectrum of light that are eyes are seeing.


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## jeffkrol (Jun 5, 2013)

Freemananana said:


> While it would be nice to get an idea, you can rough estimate based on wattage still. It's an old and out dated method, but you do get an idea of the output of the light. The biggest thing is researching similar tank sizes and see what people are running as far as the depth goes. I originally struggled with too weak of a light before I realized that the depth is what cuts down on the strength of the source.
> 
> Your light is 4500 lumens, which again is an old and dated measurement, but that should give you an idea. On my last 20g tank, I ran a beamswork LED which was 1200 lumens. It was just under 14w of power as well, with 0.5w leds. I was in the low light territory but had no problem growing dwarf sag, floatings, guppy grass, anubias, etc. You could cut your light to less than half if you are running without CO2 and likely have no issue with a decent length day schedule.





for the guesstimators.. calculators..
Lumens to LUX
https://www.rapidtables.com/calc/light/lumen-to-lux-calculator.html

LUX to "PAR"
https://www.waveformlighting.com/horticulture/convert-lux-to-ppfd-online-calculator

so lets start w/ 1200 lumens and a distance of 12". Lights roughly 36x 4 120 degree lenses
covers approx 25sq feet at 12"
517LUX..

13PAR..MINIMUM...
Assume like x1.25 for light entrainment..
16PAR..

considering you are prob. talking an equiv to an EA..30" EA is 1700 Lumens..
17.6 PAR after connsidering the new lumen amount.. 1200/1700 X say 25 per average of the 2 below at 12"
25 x .71= 17.75










What do you think???


I do prefer to "start" at the surface dimensions..and guess my way down..

Bump:


EdWiser said:


> The problem is water. [emoji3] Water can really mess with light. Water can cut the Par by 3/4 at the bottom of a tank. Also at an angle par can drop off fast. The human eye is terrible at determining how much light puts out as we have a small spectrum of light that are eyes are seeing.











In certain ranges the light falloff is fairly linear..


6" PAR x. 5 = 12" PAR x .5 = 18" PAR.. At least in the ballpark..
slope of the log function,...sort of
https://study.com/cimages/multimages/16/fderlogfun2.png
https://www.advancedaquarist.com/2013/3/review_album/image011a.png/image_full
Admittedly complicated.. 
Like by painting your back glass you massively cut reflected light that would stay in your tank..


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## EdWiser (Jul 14, 2015)

One can do all the estimating they still not as good as a meter and sensor in the water. Especially with LED’s as many of the lower priced ones many use do not have lenses to spread the light evenly.


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## *Ci* (Jun 16, 2016)

Does this calculator work well enough for a ballpark par estimate?

https://rotalabutterfly.com/light-calculator.php


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## Preeths (Jan 29, 2008)

Once you use any source of light, the brightness reduces by about 15-20% in the first few weeks. Then for the next few months the amount of light gradually reduces. You have a continuously varying Par value for the lights that are used. This is true for MH, PLL, T5/T8, CFL blubs. I'm not so sure about LED's. This may be one of the reasons no one specifies the values.


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## Bunsen Honeydew (Feb 21, 2017)

*Ci* said:


> Does this calculator work well enough for a ballpark par estimate?
> 
> https://rotalabutterfly.com/light-calculator.php


I just tried it out and it gave me 22 PAR at substrate, which feels about right. Just one anecdote though.


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