A system for sensing and measuring water characteristics or an external factor and initiating controlling the water characteristics of the body of water which may be based on external factor where the controlling of the water characteristics can be achieved through dosing or nondosing of an inactive material through an active material or dosing both an active material and an inactive material in the body of water in response to measured levels of water characteristics to enable the water to be used for either internal or external use in controlling harmful organisms.