Abstract: An improvement in a method for maintaining swimming pool water fit for use and apparatus for implementing same that is cyclical and that requires minimal amounts of treatment chemical, such method including introducing into such body of water an amount of selected accepted inhibiting chemical sufficient to raise the concentration of such chemical to a value within an established range known to destroy or inhibit the growth of any contaminant, then recirculating such body of water until the concentration of such chemical diminishes to a low point; then repeating the introduction step and the recirculation step several times with the cycle completed by the introduction of an amount of the order of twice the amount of the treatment chemical introduced at each preceding introduction step so as to dramatically change or shock the pool environment followed by recirculating such body of water until the concentration diminishes to a low point and then repeating the cycle; the apparatus for dispensing the treatment ch