I have an old jacuzzi I use as a pond and it works great. Its outside and under a deck so plants don't grow in it. I keep goldfish (about 24) in it. The depth is a good thing because it keeps the racoons out. I see their footprints everywhere! About a year ago the the plumbing basically blew. Leaking everywhere so I sealed the jets and built a homemade filter out of a 5 gallon bucket, pump and filter media. No heater needed for goldfish. Cleaning is easy with the slick surface but, so is falling in with algae! Its fun to see the goldfish come to you when you feed them. I even put some guppies in and the goldfish hunted them down like little oscars! I'd recommend one.