ChemiZee is Zeolite and can be used in all types of filters, excellent for freshwater use. ChemiZee is highly porous which allows water to pass through where a chemical exchange takes place. This chemical exchange allows ammonia to be removed from the water. Ammonia is important to remove from your aquarium in high concentrations it can prove lethal to your livestock. Always monitor the ammonia in your aquarium using a NH3/NH4 test kit. ChemiZee will help greatly reduce high levels of ammonia.