UVB lights for BD in 4ft viv

[forwantof]

My Dad has gotten his first viv for a BD called Calcifer. I have just noticed he has a 30 inch 25W 10.0 UVB tube along the top of his viv whereas I have a 36 inch 30W 10.0UVB tube - will this make too much difference? I want to make sure that Calcifer will have sufficient UV. The temperatures are ok (80F cool end and 110F basking, 90F ambient around basking).

Thanks!

[linda.t]

i would have gone for a longer one but the uv sounds like its to high up needs to be on the back wall of the viv about 6 to 8 inches from the floor.