I have just drug out an older tank from my parents basement. it has water stains near the top on all four sides i have scrubbed and scrubbed trying to get it off. i dont want to use chemicals for the obvious reasons. is there anything out there that can take of these deposits. i have gotten a lot off with a razor blade but u can still see it. thanks wife wants to set up a guppy and neon tank....thanks from us in advance....