Now save on your favorite sera water care products with this economical double pack the sera water treatment pack includes 500 ml sera nitrivec biostarter for aquariums special mix of assorted high grade cleansing bacteria for aquarium water 500 ml sera aquatan clarifies the water instantly bonds harmful heavy metals and neutralizes dissolved salts and abrasive chlorine for more information about each of these products please look in the section entitled water conditioner in the zooplu