I think it's actually sweet water. He's lived in sweet water all of his life.
Oh, I forgot one more thing: he was as fearful as a rabbit. Very anxious, if we tried to move him from point A to point B, he's struggle with all his might, flailing his legs and head in sheer terror. Now, he doesn't do that anymore, he just floats graciously, no more struggling!
Also, before, he used to sleep with his head, limbs and tail tucked inside the shell, which I think is very uncomfortable. Now, it's an EAGLE SPREAD. I keep taking pics of him, he's soo sweet!...
Of course, having read Dr. Clark's work, I wear gloves when I handle him, and if I don't, I will carefully scrub and disinfect my hands, like surgeons do (and so does my son, he has no choice, he lives with me :-))