I am about to order a bulb for my guy that should be ready to come home soon and was wondering if the screen on top of his enclosure would filter out too much of the UVB produced by a mercury vapor bulb? I was planning on ordering the 100w megaray bulb.
However, if the screen will filter out too much of the UVB, I will probably just get a fluorescent fixture to hang inside of his tank that will house a reptisun bulb.
Will the MVB bulb produce enough UVB for my boy even though it will sit on a screen?
The megaray would be fine outside the screen, it also has the benefit of UVA that the tubes really don't have. The uv meter owners group has a test report on them, they are quite strong. Typical reptile screen blocks about 35% of emissions. You'll still get more UVB than you would with a T8 tube in a cabinet fixture.
If you decide against the MVB a T5 outside the screen would be a better choice than a T8 inside the cage.