how the hell do i get rid of it i gave my tank a good scrub on sturday i've come back after being away one night and there are spots all over my rocks and some faint green ones one the glass, should i just buy some snails, i found it very hard to fight in my little one and just resorted to cleaning it properly every week,thinking about i dont think i used to have such a problem un till i started to use filtered water but im not convinced could it have any thing to do with the fact im using filtered water, am i better of using harder tap water, buy the way its in an ambient temp single tail gold fish tank