Thank you for posting in the appropriate topic...:-) I did answer you in the other post though. Here's a little more in depth info:
The brand is important. Not all bulbs are created equal.You need no less than two 4' fluorescent UVB tubes for an iguana over 1 year old. Since the strongest amount of UVB comes from the center of the tube and weakens quite a bit at the ends...the longer the tube is you get, the better the coverage. The brands to go with:
Merc Vapor: Mega Ray EB (external ballast) 60W Mega Ray SB (self ballast) 100W T Rex Active UV Heat 100w Spot( self ballast)
The EB is mostly very high UVB emissions with as much heat as a 60Wbulb produces. Very easy to control the temps with. This one comes with an external ballast which should last at least a couple of years or more. This is the best bulb on the market anywhere…period. It is more costly initially, but the bulb should be the only thing needing to be replaced on a regular basis and is comparable to other merc. vapors.
The SB produces more heat, which I don’t like because to adjust the temps the UVB source needs to be moved farther away. Still a good bulb…out-shines (pardon the pun) and ordinary UVB bulb. The only one better is the EB.