This might work for you. I know some store that has herring tanks use things like this. You’ll need a pond pump for 110 volt or a bilge pump for 12 volt. The filter container can be made from just about anything that won’t rust. 5 gal. Bucket, Tupperware. Anything like that. Drill a lot of small holes in the bottom. A big hole torts the top for overflow. A piece or foam rubber about 2 in. thick. Quilt batting on top the foam makes it a easy to clean. For minnows I don’t think the filter needs to run very long. When I get mine running I’ll run it about 15mins. a day. Any other thoughts will help me out also…..THIS WAS HARD TO DRAW WITH A MOUSE...SORRY.. Good Luck