I have a grey tree frog that I've been keeping without UVB for about 5 years now. He seems fine with his with supplements (calcium, nutrobal, and repashy vitamin a) so a part of me thinks 'if it aint broke don't fix it'.

BUT I've always heard about how good UVB is for them. The reason I haven't tried it is because, his tank is a converted 20 gallon aquarium and so the top is covered by 6mm glass.

I was explaining this to me colleague at the pet store and they said that glass only partially blocks UVB. And that if I got a strong enough bulb, it would get through the glass enough to benefit my frog. Is this true? Should I get a UVB bulb or should I just carry on with what I've been doing?