I don't know that the great wavelength debate has been solved, so I believe there are still different parties wrestling over red/blue versus green.quote:
Originally posted by William:
This is what the vendor wrote when posed the same question:
"You should definitely use a glass or similar barrier between the lights and the water. This is the only really safe way to install lighting. It will also allow you to get more light into your tank since you lose a lot more light to dirty reflectors and bulbs than you ever will to a glass top even when it is dirty."
I've always heard that cover glass absorbs key wavelengths that are beneficial to plants. That's why I've never used one with ordinary fluorescents. The consensus seems to be that safety dictates the use of a cover glass with PCs