Nitra-Zorb can be used in freshwater aquariums containing aquarium salt and in Rift lake cichlid aquariums. Nitra-Zorb will not work in saltwater aquariums. The high level of salt prevents the ion-exchange process from working properly. Do not use Nitra-Zorb while medicating the aquarium http://www.marinedepot.com/Aquarium_...FMCHNR-vi.html