Not sure how many gallons my tank is but it's 6 feet long and about 2 feet wide. It's filled half way for my 2 false maps and 1 painted. A few years back I got a pond filter. It's a huge square box that has trays for media and etc. I didn't buy the pump they sold for it b/c it was too expensive and instead got a high water output pump from Dr's Foster and Smith for maybe 30 bucks. Tell you what I have the cleanest turtle tank and they get feed in the tank too. I also have two foot long Plecos that live with them. My water always test prefect and is crystal clear. Unfortunately I don't remember the brand of the filter box and can't find a name on it but it's awesome!!!