Systems and methods that enable the responsive treatment of a body of water with an aqueous halogen solution whose composition can be varied as a result of input from sensors monitoring the water being treated. Various sensors are immersed in the water so that the physical, chemical, and microbiological properties of a body of water being treated can be measured. Information from these sensors is used to produce aqueous halogen solutions of varying composition which are then injected into the body of water being monitored for the purposes of ensuring the body of water being treated is being effectively disinfected.