Please help!! We have done everything we know of, of how to rid our tank of it's disgusting odor...It smells like wet towels or poop...I dunno...It's so gross. We have 11 huge goldfish and 2 algae suckers(?) It's a 15 gallon tank and we have 2 external filters. We've had to change the filters almost every other day and this is getting pretty expensive! The smell stays gone for one day and then it's back again :huh: I'm thinking that we need a new tank....I am getting really tired and grossed out with this smell! Oh ya...we've tried the odor solution and still no luck! Can anyone help with this dilemma?! Thank you in advance 