You will also need some sort of platform like a flat rock or floating island with a UVA/UVB light.
This will be essential for your turtle's health because your turtle needs vitamin D to absorb the calcium that it gets. The turtle lies on a platform to get dry and absorb the UV it gets. Make sure to put the light on top of the basking area(flat rock or floating island).
Some there are different kinds of UV lamps.
Some emit heat and UV but are EXPENSIVE!
Get one that you can place far enough away(Depends on the watts.) from the water and close enough so that the turtle gets UV.