Currently have a 20 gallon tank. I am getting a 10.0 tube light. Should I mount this in the tank or keep on top of the screen. I was going to put in the tank but I read that 10.0 is strong enough to be outside the screen. Any suggestions.
Either or should be fine. I mounted mine inside the tank because I heard that the screen can actually block some of the UV Rays that your dragon needs.
You'll get more output reaching the basking area by mounting inside the screen (the screen blocks around 35% or so) but with such a small tank it probably won't make a huge difference. Just build a basking site that gets up close within about 6'' of the bulb and it should be fine. Having a fixture with a reflector makes a difference too so I suggest using one.