I have an established fish tank, about 2 1/2 years. 55 gallon. I have a terrible oder. I can clean it, change all filters, put in salt and within 3 days I have an oder. It is hard to describe it, it is not like the start up oder you get after a week of a new tank. I am ready to get rid of tank because I am frusterated with this. Can anyone help me?

Hello I think it might be because of real plant I probably didn't help but anyway