Placement of lights

[Quincy]

I have a 100 gallon reef tank that is 24" deep. My lighting system consists of 2 250 watt MH and 2 VHO PC. What are the general thoughts on high to suspend the fixture over the tank?

 

[Krish]

I had my dual 250w halides suspended 9 inches above my water and it was fine. Some said they had theirs even lower with no issues. I think you wouldn't want to go any higher than 12 inches especially on a tank 24 inches tall. Just a thought...