My turtle sleeps in the water at night all tucked in her shell . Are you still using a red bulb for your UVB light? They do not produce UVB so if that is the case you will want to purchase a light that has UVB ASAP. They sure lay around basking like life is good don't they.
Here's how Sky, one of my RESes, sleeps underwater, tucked beside his favourite rock.
