How fine is the sreen on the cage? Too fine of a mesh will filter out too much UVB. Also, since you have a fluorescent UVB, be sure it's closer than 12 inches from the turtle, otherwise it's pointless. Fluorescent UVB lights only have a range of about 10-12 inches. Beyond that the turtle won't get enough UVB exposure. Just to be safe, double check the light and make sure it's a UVB and not just "UV" or "full spectrum". If it doesn't specifically say "UVB", then it's not a UVB. Personally, I always reommend a mercury vapor bulb for use with turtles. It has a much better range and concentrates the heat and UVB in one spot, eliminating the need for a seperate basking light and better simulating the sun. They're a more expensive bulb, but they're actually cheaper in the long run.
You'll also want to make the water deeper. At least twice as deep as the turtle is long so he can swim. I'd also recommend getting rid of the rocks, but that's up to you. They may look nice, but you'll have to clean the cage out at least once or twice a week, and rocks are not only going to get in the way, but they'll harbor bits of uneaten food, turtle feces, and bacteria. Turtles are also notorious gravel swallowers, though he looks too small to swallow any yet.
Here's a thread that I posted in a while back that you may find helpful:
Baby Red Eared Slider
Enjoy the little bugger! She's a cutie
Well, I say 'she', but I think she's too small to accurately sex at this point. Males will have longer claws, the cloaca will be further from the body on the tail, and their red stripe is not as thick.
