Answers to this question seem all over the place and I want to make sure my cage is set up right. The way I have it now is I have the Reptisun t5 ho 10.0 mounted on the on top of my screen lid in a reflector hood. My bearded dragon sitting at the top of his basking spot is probably about 10-11 inches away from this light. Does this distance sound ideal, or should I lower or raise it?
I recently contacted Zoomed on this topic. Here is the answer I received from a Zoomed rep:
The T5 Reptisun 10.0 bulb produces UVB that can reach 18-24 inches away from the bulb with a screen top. Without a screen top the UVB can reach 36 inches from the bulb. As long as your beardies are within that range with a screen top they are getting the UVB they need. I would also recommend having it either towards the back or front of your enclosure and not the middle. Putting it in the middle does not create enough of a UVB gradient for your beardies to get away from the bulb if they need to.
Through a screen, 10-12'' is OK. The T5 puts out basking levels of UVB at around 12-14'' without a screen based on my testing and other test results I've read. Taterbug has a good chart that shows appropriate distances for different lighting configurations. https://sites.google.com/site/thelizardmadness/lighting-guides