Compact Fluorescent Bulbs initially got a very bad rap when they were first introduced to the reptile marketplace, as early designs emitted a spectrum that could damage a reptile's vision. That was corrected long ago, and modern compact fluorescent UVB bulbs are perfectly safe to use with your pets. Think of a compact fluorescent bulb as a linear fluorescent bulb that has been wrapped and folded around itself several times. Much of the UVB emitted by the bulb is transmitted back onto the bulb, and is not focused or very directional. Because of this, while using a fixture with a reflector will greatly increase the amount of UVB reaching your reptile's enclosure, Compact Fluorescent UVB bulbs are not horribly efficient and producing UVB radiation. Generally, CFL UVB bulbs should be used at or near your pet's basking spot, so that the animal is exposed to UV while basking. Compact Fluorescent Bulbs are inexpensive when compared to other reptile UVB lighting products, and are self ballasted (they'll screw into most standard incandescent sockets). CLF bulbs are energy efficient, with most models using only 13-26 watts. Compact Fluorescent UVB bulbs should be replaced every 6 months. As a general rule, reptiles or amphibians should be able to bask within 12" of the bulb.
Full Spectrum Fluorescent Bulbs For Reptiles UVB & UVA
ZooMed T8 and T5 Repti-Sun bulbs can be used. However, Exo Terra Repti Glo tube lights have changed their specifications frequently in the past, and no current data is available. However, after rooting around in the UVB Meter Owners Yahoo! Group, the data hasn’t been good with regards to short wavelengths emitted and rapid decay of UVB. So we do not currently recommend them because of the possible health risks of improper wavelengths or insufficient UVB.
Reptile UVB Bulbs: Insights from Herpetologists | That Reptile Blog
2. As the distance between your pet and the UVB bulb increases, usable UVB radiation decreases rapidly. Most bulbs provide UV levels and readings at a recommended minimum distance from the bulb (generally about 8-12" for linear or compact fluorescent lighting, and 12" for Mercury Vapor or Metal Halide UVB bulbs). Make sure to consult the specific manufacturer's recommendations when deciding what UVB bulb to use, and take into consideration the distance between the bulb and your pet reptile before you choose a UVB bulb.
Reptile UVB Lamps and Bulbs - A Reptile Lighting Product Guide