If the UVB is a T 8 it needs to be inside the tank --- T 8' s are not strong enough to go thru the screen - it needs to be inside the tank approx 6-8 inches directly above him- if its T 5 it can sit on top of the tank but that depends on the screen --- the screen needs to be a wide holed screen NOT a fine mesh like a screen door --
distance plays a role here as well ---- NO more meal worms please --
Karrie
As Karrie suggested, it really would be much more effective if you could mount the tube UVB
underneath of the screen so that he receives direct exposure instead of filtered light through
the screen top.
How is he doing today?