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!