AquaSafe Plus works instantly to make tap water safe for fish. The patented PLUS BioExctract formula contains natural biopolymers and essential vitamins and minerals for healthy and clear water. Substances in tap water (like chlorine, chloramines, and heavy metals) that are dangerous to fish are removed or neutralized. Powerful slime colloids reduce stress in fish by protecting gills, delicate membranes, and helping heal wounds. Tetra AquaSafe Plus should be used when setting up a new aquarium, and with every partial water change or evaporation replacement.