How high should fixture be?

[Jeppeterpan]

I have a 8 bulb t5 fixture, but I'm only running 6 bulbs on my 72 gallon. I'm running 4 blue plus, aquablue special, and a purple plus. I noticed that since switching fixtures, some of my corals have begun to bleach out. The fixture is using its factory legs which puts the fixture only about 4-5 inches off waters surface...how high should I mount it because obviously its too close to waters surface. Thanks r2r!

[Jeppeterpan]

Oops sorry. Tank is about 20 in tall and is a mixed reef. Just thought I mention it before anyone ask....thanks again!

[mcarroll]

What light (quantity and quality) were your corals under before?

Regardless, unless you have a good way in mind to raise/lower the light just adjust your photoperiod instead.

Without knowing more of the history, I would suggest starting out with 1 or 2 hours of light per day. Add an hour per day about every few days (try to have at least 4 hours of light within a few days) until you're up to your normal photoperiod (8-10 hours or less recommended). Once you're above 4 hours per day, I'd consider waiting a week between each one-hour addition. (Less time between additions might work and more wouldn't hurt anything.)

Since they've already started bleaching, don't get high hopes for an immediate recovery. You may get lucky, but often a coral will take weeks to months to fully recover. By that same token, don't throw away an all-white coral...months later a comeback is eminently possible. Keep the tank otherwise healthy and you shouldn't lose anything.

-Matt

[Jeppeterpan]

Was running kessils, but ditched them to go back to t5s. I had cut my photoperiod, but will cut back some more. I was gonna put hanging brackets, so I guess I have a reason to not be so lazy now. My coral ( mostly Lps) haven't bleached yet, but you can see color fading. Just wanted to make sure that I didnt roast my tank! Thanks for the advice Matt. Any other advice much appreciated...thanks again.