Years ago Sanjay Joshi and a few professional hobbyists were talking about light and its effects on corals and other photosynthetic organisms..What it basically boiled down to was natural sunlight hits the equator at a around a 20-22 degree angle the reef never gets hit with direct sunlight,it is mainly reflected and refracted light,If you ever look in shallow water you see glimmer lines,the light in those glimmer lines are up to 10 times more powerful than direct sunlight,If you would like to do an easy experament take a stroll along the water in about ankle deep water during summertime,for about an hour at noon,What you will find is the tops of your feet are burnt,yet the rest of your legs are fine,why is that,well the water acted as a magnefying glass,and your feet where the bug Now because of the depth the light has to penetrate and compounds that are in or make up saltwater different waves are filtered out....Anything you put between the light source and the organism you are keeping,can and will change the spectrum and the intensity of light,As Garbonzo pointed out get a par meter and test the effects on what you want or trying to do,Water can and will destroy in the long run metal fixtures,You have a very powerfull light source so I don`t see why you could not have it higher above your system,with an open screen top that fits flush with the frame around your tank,lets all the light in and keeps all of your fish in,helps with evaporation to keep your tank cool..Just my two cents
