Bee0912;3891478; said:But it has to be in the water to find its way on the glass. UV= not in water so not on glass.
It won't keep algae from growing on the glass.
I use a UV in my 1500 gallon tank, and it keeps the water clear, but I have plenty of algea growth on the sides of my tank. It would be even more so with glass because of the light.

