If the shell is improving, I think I'd wait. If I needed/wanted to add salt to the tank at some point, I'd use aquarium salt (but I'd wait). BTW, a fuzzy shell isn't a sign of growth. If the skin on the arms and legs looked wispy and translucent in the water, that could be a sign of growth (skin shedding).
The Reptoguard probably isn't going to to much, if anything. Keeping the water clean with changes is the best thing to do.



