Do you know what brand name? I have two of the zoomed powersweeps, and they have been working okay for me. Many people will tell you that they stop sweeping after awhile. I only cleaned mine once and one did stop sweeping for about two months, and then all of a sudden it started sweeping agian. It was so funny because my snails would get on the sweeping part of it and clean it, and they would be moving back and forth, I always wondered if they got dizzy. LOL But even if it does stop sweeping it still pushes out water, so in my opinoin still working.