i got a mogul 175 watt mh reefstar 14k pendent /fixture thing.i am going to mount it about my 20 gallon HIGH for frags. how high above the water could i mount it so i will have no heat issues?
I think that is something that you will have to play with yourself. Because of all sorts of variables air temp. in the tanks location, how big of sump, and a crap load of other stuff. I would suggest starting at say 6" and work yur way up.