I have a 110 gallon reef tank being lit by metal-hallides (2x250w) and blue 4 actinic T5s.  My light schedule is T5's starting at sunrise for two hours, then MHs for 8 hours, then T5s for two.  Obviously the lights get very hot and I'm trying to reduce the water heat as much as possible; they're currently 10.5" away.  I know LEDs would be better, but they're not in the cards right now.

The question is:  How high can I raise the lights while still being effective for photosynthesis (penetrating 31" of water)?  Is there maybe a 4'x2' hood that could possibly focus the light straight down, allowing me to lift the lights higher?

Also, if you have a recommendation for an alternate light schedule, I'm open for suggestion.