Yellow belly slider belly turning pink

by Lindsey
(Paltka,Fl, Usa)

I have a yellow belly slider that is very active and eats great he has a clean tank I clean it about once a week he has a filter but its not the best, My question is upon examining him I noticed his under side on his belly is turning pink, I have found a vet in the area just trying to make sure it is serious enough to spend the money and I need to know if I could treat it at home