[jcolletteiii]

I've been wondering if there is a way to estimate the PAR output under a single AI module for any given depth and at any combined output percentage of blue and white LEDs. I asked AI if there was a means of calculating this, and they responded that there was, as long as the 100% PAR value is known for the depth you are interested in calculating. The formula they use is quite simple: (PAR @ 100% * 0.65) * blue Percent (in decimal form) + (PAR @ 100% * 0.35) * W Percent (in decimal form) = scaled PAR (+/- 10%). They say that in their testing, this formula is fairly good at predicting PAR. So, for this formula to work, you must have a reference set of PAR measurements taken at all depths of interest. I just took teh measurements given on the first page for 6, 12, 16, 19, and 24" and extrapolated them by taking the difference and dividing by the number of bins between measurements. This gives the following estimated PAR measurements for every inch increment from 6" to 24" depth.

Par depth (in.)

1650 6
1603 7
1556 8
1510 9
1463 10
1416 11
1370 12
1256 13
1143 14
1029 15
915 16
840 17
765 18
690 19
664 20
638 21
612 22
586 23
560 24

So, if you want an estimate of the PAR at a given depth for a given percentage of white and blue, you just take the 100% par value for this depth, and multiply according to the given formula. So, for example, I want to know what the PAR is at 12" below one unit running at 20% white and 55% blue. So, I would use the 100% value for 12" depth, which is 1370, and plug the following into the formula:

estimated PAR at 12" = ((1370*0.65)*0.55)+((1370*0.35)*0.20) = 541

Of course, AI gives a +/- 10% margin of error, so the estimated PAR value should range from 486 to 595 at 12" depth with the settings mentioned. It would be great if someone with a PAR meter could confirm this estimate is valid. If so, this formula has the potential to help out quite a few people.