Originally Posted by
saltyfish808
http:///forum/post/2479736
What is a good watts to gallon ratio for metal halide lights? Can you over do it?
Yes, you can overdo it, but usually not with anything below 10 watts per gallon. Overdoing it causes excessive heating of the water, algae growth, and electricity waste. In extreme circumstances, it can burn your corals or fish.
Apropos, watts per gallon is an outdated measurement for lighting, but it still works pretty good for halides.