John,
Maybe we should fill them with ice and put are fish in there at least it would keep it cleaner with using them, but then people would have to move around so I could open the box.

What I did do was I bought screen which is used for your drain on a clothes washer to catch lent. I put those on the drain in the fish cooler and took wire ties to attach them. It does help keep some of the grit and grime from the pump. I still have to clean the filters on the pumps quite often.