cation exchanger

Definition: Cation exchanger is an ion exchanger that exchanges only the cations in the aquarium water, replacing them with acidity-forming hydrogen ions. It is suitable for softening water with high carbonate hardness and low non-carbonate hardness. The water softening process produces a lot of carbonic acid, which is removed from the water through intensive aeration. Water thus treated has a low pH, and should be hardened with tap water until it has a more neutral pH.