Overtime the diaphragms in the Airmax PondAir Aeration Kits will wear out or fail leaving you with a running aerator that produces no air. Replacing worn or damaged diaphragms will restore air output and keep your aeration system running like new. We recommend replacing the diaphragm every 6-12 months. These replacement mini diaphragm kits are guaranteed to fit the following aeration systems: Airmax PondAir Aeration Kits.