a method and composition are provided for the operation of an evaporative cooling tower with minimal , or no , blowdown . in some embodiments , the method involves using sodium cation - exchanged softened water as makeup water for the cooling tower , providing a bypass filter for suspended solids removal from the cooling water , treating the cooling water with a composition for control of corrosion and deposition , and using an effective biocide for control of biological growth within the cooling tower system . in some embodiments , a composition is provided that comprises amps acrylic terpolymer , sodium silicate , phosphate ions , and polyphosphate ions . when dosed at the recommended levels , the composition controls corrosion of cooling system materials to generally acceptable levels in spite of the extremely corrosive environment resulting from the cycling of sodium cation - exchanged softened water in the cooling tower .