I've had two battery powered ones for several years. They are called Nutramatic. I use flake food and have only had problems with the moisture making the flakes clog once. When I only had regular florescent lights, I left the top hood open for more circulation the keep it dry. Now that my tank had VHO, the heat seems to keep them dry and no moisture problems. Just came home from a 10 day vacation and the flakes were still dry.