Originally Posted by Psychocircus91
thanks mr X. your opinion is certainly valued. My concern is that they recommend hanging them about 10" above. If I do buy these fixtures for a glass canopy should I get the standard, 60 degree optics, or 90 degree optics? Does it matter?
PS I have a standard 75 gallon.
choice of the degree of the optic depend on your needs. smaller degree, provides strong focus spot light effect directly under the fixture. It has higher PAR /PUR due to the concerntration of the LED
light beams. However, it gives up a lot of spread. Some people love how that can have spot light feeling with strong shimmering effect and doen't mind some shadow on the sides.
On the other way around, larger degree lenses will spread the light more evenly and can light up larger area, but you will have less PAR /PUR under the fixture. It would be up to you what you think about your tank. Afterall, it would be yourself and your family enjoy the aquarium, just like choosing kelvin of fixture, do you go with 14000K or 20000K, both would work, but might have different impact on viewing