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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.

Gary
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Not knowing what type of corals you have (soft vs. hard) this is what I've come up with:
If you have a hybrid fixture (metal halides/t5 combo body fixture) you will want them about 6-7" inches from bottom of the bulb to top of the water (most of these that come with legs are 4-6" which is okay but not optimal). If they're two different fixtures (a better result for your reef) mh should be 9-10" from bottom of bulb to surface since you have 250s. The t5s 4-6" (you could theoretically do 3" but it's common it'll get too hot, even with a cooling fan), plus you want to keep salt splashing down to a minimum to extend the life of the bulb (usually lasts about a year in a good setup).

I don't see anything with your light schedule being 2,4,2 especially if you're concern is heat, then keep it that way...it's just more common to see 4,4 hour interals- mostly for convenience

Christy B.
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