new beardie, UVB on top or inside

We received a 5 month old beardie from a breeder but I'm still not sure what is the best location for the UVB lighting - Repitsun 10.0 T5 22" housed in a Reptisun 24" Hood. It is located on top of the screen (Reptizoo 36 W x 24D x 18H) and basking spot is 8-10" from the top. Am I better off putting the UVB inside the tank?

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If the basking site is already only 8 inches away, it's the right distance to be on top of the screen. If you put it under the screen you will need the basking site to be about 12 inches away.

-Brandon

Thanks. Is the UVB distance of 12" based solely on the basking height or how away from the ground? Seems he spends most of his time in hide or on the ground that's why I'm asking. Also, he is about to shed so maybe he will bask more afterwards. If I put it inside his tank, basking height would be 4-5 inches which is doable but the halogen bulb would have to be on full power to reach temps of 100F-110F at only 4-5 inches above ground.

In regards to setting up UV distance, it's based on wanting to achieve a certain UVI level at the basking surface. A few factors can affect what UVI level is on a surface such as the strength of the bulb, if the bulb is housed in a fixture with a reflector, if there is a screen in the way.

Luckily, since there are not many scenarios or bulb types out there, we pretty much know what kind of UVI levels to expect out of specific bulbs given a set of circumstances.

Most would agree that a UVI level around 3-5 is ideal at the basking surface for a bearded dragon. An unobstructed T5 10-12% bulb in a reflector housing can achieve this at a distance of 12-15 inches away. At 8 inches away, it is much higher than a 3-5. So in your case, the screen blocking some of the intensity is actually a good thing as the average screen will cut down the UVI level by near 30%. That's what makes 8 inches away from the basking surface an ideal situation in your specific case.
If you mounted the bulb inside the tank, and your basking surface was now only 4 inches away, you'd fry your dragon with UV. The UVI level at 4 inches away is extremely strong and extremely damaging to cells.

We really only worry mainly about basking surface UVI. Your dragon will have lesser exposure throughout the tank. That is not only ok, it's ideal. UV, while necessary, can also be harmful. And it's important for there to be a gradient for UV just like you have a temperature gradient.
In my tanks, I have a UV gradient down to 0 (shade) on the cool end.

-Brandon

Thanks Brandon but I meant the basking surface would be 4-5 inches above the ground so 13-14" away from the basking site if it was mounted inside the enclosure. No way I would put the basking site up higher and what is right now considering the screen is blocking 30% levels. I was just curious about using the basking height for optimums UVI levels instead of lower or ground level where he spends most of his time.

Ok I understand

Basking surface is the main concern. As long as you do not have an abnormally tall tank, their will be sufficient levels of UV throughout the rest of the tank, even near the bottom. But like I mentioned, a UV gradient is beneficial too, so having areas near the bottom and cool end where the UV level is low or non-existent is beneficial too

-Brandon