Ultraviolet Lighting Effects on Marine Aquaria

[beth]

I know that the manufactures of marine aquaria lighting [MH and VHO] assert that the marine bulbs sheild aquarium habitates from most direct UV, however, I've been reading on this topic and there seems to be a lot of references that claim that, while hobby bulbs do reduce UV, it does not reduce UV contact enough and that other sheilding is preferable. Opinions?

 

[mr . salty]

I have never really worried much about this. How much protection from UV do they get in shallow reefs in the ocean with the sun blazing on them at high noon???????I gotta think our puney little bulbs are no match for this.

 

[beth]

Some of the stuff I read covered that in terms of many reef creatures having natural barriers to the UV that you can't achieve in a closed system. Additionally, near-surface reef environments are specific to certain species that live in that habbitat, as opposed to other reef creatures that live in deeper waters. There are a lot of posts here about corals bleeching suddenly, etc. Perhaps a simple barrier would eliminate these proplems.
Also, I am thinking, too, that a bearier would significantly reduce heat on water, eliminating the need for a fan that basically causes a good deal of evaporation. I checked out the LFS reef setup this week and took a good look at the lighting setup. 2-MH bulbs, guessing around 400watts each, but covering the lighting was a 1/2" plexi. I put my hands right up to the plexi [not touching it] and got very little heat, and at water surface no noticable heat. The MH's were ventalated with fans within the housing of the hood off to either side.
Just a thought.