Turtles have white feed and heads

#00 gallon preform. I have 3 turtles abot 5 inches. 2 have just gotten
White feet. Look like shedding skin. The head of one has it only where
its head is poking out of the water. the rest of its neck is fine. Is
this lack of basking? I have 2 basking areas but we only get 4-5 hours
sun at the pond. I have a uvb light I can put out after no rain. But the
feet look weird, whithish. Temp is 78-82 . The eat nightcrawlers and
seem fine. Any Ideas? Thank you