I just read something saying that UVB strip lights are the only UVB light source you should use, as the UVB compact bulbs are no good. Is this true? What makes the strips better than the bulbs? Light dispersal?
Also if I added an extra reptisun 5.0 bulb to my fixture (for added plant growth) would this harm the cham? I have heard its not good, but just wondering why.
There was a problem a few years ago with the formulation of the phosphors in some of the CFL bulbs that were available at the time. The wavelength range that comprises UVB is 280-315 nm and peak synthesis of vit D3 occurs upon exposure to a wavelength of 295-297 nm. All UVB has the potential to cause damage to DNA, proteins, etc., but the shorter the wavelength the more damaging the radiation tends to be.
The problem with the old bulbs is that they produced too much short wavelength UVB, in the 280-295 nm range. As a result, they caused severe eye and skin damage to many animals, and not a few deaths. This problem had nothing whatosever to do with the fact that the bulbs were CFLs, and everything to do with the particular formulation of the phosphors used to make them.
The problem has since been corrected and all recently manufactured CFL bulbs (to the best of my knowledge) should be just as safe as linear fluorescent bulbs.
Having said this, either linear or compact fluorescents can be more advantageous depending on the particular situation. Because a compact bulb is coiled, it produces a steeper gradient than a linear bulb over modest differences. As a result, it's easier to direct the UV and easier to produce higher UV intensity, which might be useful if one is trying to hit a particular spot. Alternatively, it can be useful to have a more even UV field over a larger area, granting that the peak intensity is inherently lower because the UV is more spred out (over similar distance from the bulb, of course). Both can work, if one considers the different properties of the light field each bulb creates. A linear bulb creates a more even field of modest intensity UV whereas a compact is more like a spot bulb that creates a higher peak intensity and sharper gradient.
Regardless of the bulb used, I'd ensure that the animals can bask in the UV light and their basking bulb at the same time, and that they can completely retreat away from the UV light when they want to.
As for an extra adding an extra Reptisun 5.0 bulb, again, it depends on the context. Having two bulbs instead of one will nearly double the UV intensity you get, as well as widen the light field. If the animal can easily get away from bulbs and get shelter from the UV light, I wouldn't expect a problem. If the animal cannot get adequte shelter, it may get too much UV exposure. However, this is possible regardless of how many bulbs you use.
Most of the bulbs we use, including the Reptisun 5.0, produce pretty meager UV intensity relative to what the animals get from full sun in nature, and the intensity even in the shade rivals what our bulbs produce. Passing the light through screen, which is the norm since we usually put the lights on top of the cage over screen, can further reduce the UV intensity by easily 50%. In that case, the UV intensity can often be so low it would be a good idea to use two bulbs in many situations.
The key is choices. The animal has to be able to bask in the light (an basking area that is hot+UV and one that is cool+UV is a good idea IMHO) as much as it wants, and also completely retreat from the UV and get shelter. If it can do those things, most bulbs and situations will likely work well. If it can't do those things, problems are possible regardless of which bulb or number of bulbs are used. Your setup sounds fine to me, as long as the animal has choices.
cj
