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.