Not having one of these units yet, I will give you the simple mathematical formula to calculate maximum hieght to hang them.
First thing is to understand the lenses. They tell you the -3dB point on the light beam. That is to say, how far to each side can you go before you get to 1/2 the light energy available. So if you have a PAR value of say 50 directly under a LED
, then at the -3dB point you will have 25. Nice to know, but doesn't help you hang your lights.
Measure the distance from the last row of lights to the front or side of the tank, whichever distance is less. So a std 55 gal
is 13" by 48". LED
is 8"x16" each (2).
48/2=24" section - 16" LED
= 8" gap / 2 = 4" each side gap.
13" - 8"LED
= 5" gap / 2 = 2.5"gap Front and back. (smaller number).
It appears that the rows of LEDs are about 2" inset from the edge of the light, so add that to the gap and get a 4.5" GAP.
If you have 90Deg optics, or 45deg from centre, then math says
Height = Gap/Tan(45) or Gap/1
Height = 4.5"
Height = Gap / Tan (60) = 2.6"
60 Deg Optics
Height = Gap / Tan(30) = 7.8"
If you hang them higher than those distances, you will have more light spilling out of the top of your tank. Any lower and you will not get optimum spread to the edge of the tank, but at least the light will be in the tank. So lower is better than higher (except for maintenance).