What are some of the better aquatic turtle setups?

I have a western painted turtle who is about 5-6 inches in length. He is in a large clear plastic 30 gal tub. I have a basking area, a uvb lamp, a place for him to go if he does not want to be in the light, and some pebbles/large rocks for him to climb on. I want to know what I am missing or if there is anyway to improve his setup. Thank you.