Water conditioner for fish-friendly water rich in mineral substances. Toxic substances such as chlorine and heavy metals can get into the aquarium water with every water change. Even our well-monitored drinking water often contains such substances in concentrations critical for fish and other aquarium inhabitants. sera Aquatan immediately conditions tap water into the fish-friendly, healthy aquarium water. It removes harmful substances such as chlorine and chloramines, binds heavy metals (e.g. copper, zinc, or lead), and protects against ammonia. At the same time, it adds important mineral substances in a bioavailable form to the aquarium water, which is to the benefit of fish, plants, invertebrates, and useful microorganisms.