hi i am not sure about that but i found out about uv lights that if the uv light is more than 6 inch's away from the ig it is hardly getting any uv rays ,and if u have a mesh in front of the uv light it is hardly getting any use out of the bulbs.. also if there is a plastic screen in front ov the uv light it has the same affect,,if u buy a reflector for the back of the uv light it will help ...
think but not sure that a 5.0 should do the job...5% uvb 30% uva....you don't need a 8.0 as this is for desert species and the 2.0 is too weak...just make sure you have enough lighting maybe two bulbs esp in big vivs....to be honest the best type is natural unfiltered sunlight but not always possible!
personnally the best lighting you can use is a zoomed powersun. my wd had mbd when i got her and she looks healthier now than most. it brings out their colours fantastically and produces heat aswel. also when the lizard basks under the light it'll be getting warmth and uv at same time just like it would in the wild. the uv rays also reach upto 6ft so are perfect for larger vivs.
and no i'm not a sales person for them, just use them with all my reps and think they are great.