What would be the best way to filter 10-15 tanks that will be in a rack system? 3 shelves right on top on another with 5 tanks per shelf. Each tank is 20 gallons. I dont have a bigger tank to use as a sump/wet dry etc. But I do have access to these. these barrels are 55 gallons and are food grade. Can something be made out of these? Lids don't come off and there are 2 thread in openings on the top.
Ideas?
Ideas?