I have two baby RES, Yoshi and Yumi. Yumi developed white spots on her shell when I first moved them into an aquarium. I think she got the white spots because she was a scaredy cat and spent practically all the time in the water. She never allowed her shell dry off. When basking, she would hang halfway onto the turtle dock and halfway in the water. Yoshi never had the problem. Yumi was the pretty turtle, but it looked like the white spots were slowly eating away at her shell.

I went to Petco and bought the ZooMed Turtle Sulfa Dip. After a week of treatment, all the spots disappeared.

It did take a little while for her colors to come back and there is one place on her shell where I can see a slight indentation where a spot had eaten away.
Since then, Yumi isn’t such a scaredy cat anymore. Now, she’s a piggy. She’ll spend hours on top of the dock basking. And, she doesn’t scurry into the water every time I walk by, except to beg for food.