Hi Corry! For your tank, you could use vinegar to remove the water stains (tips by John Clare). Just make sure you remove the frog when cleaning it. And from this point on, if you are using tap water, make sure you dechlorinate it by leaving it in an open container for at least 24 hours before using it.

Here's an article that might help you on how to care for a Gray Treefrog: http://www.frogforum.net/tree-frog-c...ysoscelis.html

Eric