I have a 38 gallon fresh water tank... as i said earler 3 tinfoil barbs..ranging 6-8 inches..1 blood parrot..1 gold 1 blue and 1 pink kissing gourami and 1 silver dollar..up keep on this "busy" ahem..tinfoils too big but I wont get rid of them.. tank...Rena Filstar XP needs cleaned out and rebuilt about every 10 days or so..vac about every week..Someone mentioned a protien skimmer for the water saying it would cut down on the nitrates and keep the tank cleaner..I thought they were more for salt tanks so I asked around, I get mixed results some say yes it will help with fresh water too, some say its a waste of money it dosent do anything in a fresh water tank...