I have been using this calculator, and so far it has been very helpful, thanks! I did not expect 60 degree optics to reduce par by half, but in using the calculator yesterday I think it said about 37 Micromols for two rows of LEDs at 4 inch spacing with 60 degree optics, and 90 micromols for 40 degree optics. Is that right?
Unlike a scaped aquarium, this tank has rows of plants from front to back instead of side to side. As a result, the front and back have to be lit pretty evenly. I'm also worried about light getting lost in the middle due to the seam on the glass lid. With a single row of lights in the center, I would expect the plants near the glass to not receive much light with 40 degree optics, is that correct?
If the light is placed 8 inches above the tank at 4 inch spacing (two rows), will the spotlight effect be dramatic? The tank has so many plants that there is not much open water space to really see beams of light on.
Also, would a glass lid reduce or amplify spotlight effect?
Could I use a mix of optics, like 40 degrees near the ends tho reduce light on glass and 60 degrees near the middle?