I wanted a grow out tank for my pbass and other fish, so I decided to build a frame with a pond liner. Its 72x72x24, roughly 500 gallons. I'm still working on what kind of filter to use and how much insulation. Keeping it heated to 80 degrees is gonna be a pain but I have several heaters I can use. I'll also put a plastic lid on the top to keep down the evaporation rate. Here's a few pics of the build...not quite done just like all my other projects lol. The last couple pics are of my tempoarary pond...Its pretty ghetto, but it gets the job done! Any suggestions on filtration?