UVB Lighting Advice

[annieCastanon]

I'm concerned about my UVB set up. I have a 40 gallon tank with a reptisun 10.0 it's 36"in long and runs across the entire tank. the box says it's a 25 watt T8. Here's where i'm second guessing myself, I have the bulb in a reptisun hood sitting on THE OUTSIDE of the tank right on top of the mesh cover. is it ok to have it sitting on top like this and not on the inside of the tank? I know that the top filters out some of the uvb but i'm hoping enough is going through to keep my beardie healthy. The tank came with a foam background that looks like rocks so my beardie is able to climb the wall and get right under the light if he wants.I've added a pic of him up on the wall close to the uvb bulb but he rarely does this so im kinda paranoid that he might not be getting the proper uvb because the bulb isn't on the inside Any thoughts?

P.S. Thank you guys so much for answering my questions in the past. Im a new beardie owner and just want to make sure i'm getting things right.

 

[CooperDragon]

With a T8 the optimal output is within about 6-8'' of the bulb. The mesh top will intercept maybe 30% or so of the UVB depending on how dense it is. I don't advise allowing them to get closer than 6'' but if you have a branch or something that will get within 6'' of the bulb it should be OK. If you need to provide UVB at a greater distance I'd switch to a T5 which as an optimal output at 12-14'' and can produce good UVB exposure through a mesh top.