How far from water should I have my lights?

[stlouisguy]

So far no heat issues, but as I have never used 400 w lights before, have no idea how far off the tank to have them. Right now the bulbs themselves are about 5" off the water line, sould I raise them up to 8" or more?

Thanks

 

[DrBDC]

Maybe this will help you decide according to the reflector type and coverage.

http://www.advancedaquarist.com/issues/mar2003/feature.htm