Penn-Plax Ammonia-X Replacement Zeolite Media Cartridges (2 Pack) – Choose E, Undertow and Perfecto Perfect-A-Flow Filters or Universal – Provides Chemical Filtration for Modern Aquariums (E Filter);

Ammonia-X, Ammonia Removing Undergravel Filter Cartridges is a quick easy disposable cartridge which acts as a lift insurance for your fish. Ammonia Removing Undergravel Filter Cartridges are made with top quality zeolites which work to eliminate the top fish killer ammonia. Undergravel Filter Cartridges solve the problem of overfeeding, over-crowding and foul water conditions. Filter Cartridges fit all Undertow "E" Filters.