Water volume Vs. par

[Rcat]

Does water volume adversely affect Par? I watched BRS video on Hydra 32 lighting. I have a 180 with 2 center braces. I placed my 3x32’s center of each section, 14 inches off the waterline running a suggested setting for a 60 gallon cube. I found a difference of 30 par@center.

Is 30 par normal? Never expected identical results, however it did leave me wondering.

 

[laverda]

The center brace is probably the cause, assuming it is 30 less in the center. It will get worse as algae and salt build up on it. You can make up for it some by moving the outer lights a bit closer so the overlap the center LEDs output area. Or just turn that light up higher.

 

[Brett S]

Water volume doesn’t directly affect PAR. However it does kind of indirectly affect PAR. PAR is greatly reduced as the light travels through the water, so a deeper tank will have lower PAR at the bottom than a shallower tank. Additionally, the light only spreads so far from the center of the light, so a wider and longer tank will have less PAR at the edges than a narrower and shorter tank.