Now that the medications are over, I want to put my snails back into the main tank. I have done a couple of 25% water changes and want to know how many more to do before putting my snails back in. Is there a test for this?

I don't know about other medications, but I know there is a test for the salt level, I've seen them in pet stores.

Have a look at Pelvis-Popcan's post in this thread about a salt test.

salt

Thanks guys. Emma, I love the purple and red fish!