a redox sensor measures the redox potential of the bathing water. The redox potential provides information about the oxidation or disinfection effect of the water. The sapphire system doses  automatically the necessary amount of chlorine to obtain the desired redox potential.  For  the public area  amperometric chlorine sensors are also used, which measure the actual free chlorine value in the pool water. With a high-precision control algorithm, the SAPHIR system reduces chlorine consumption to the legal minimum and ensures that the water quality is kept constant even under high loads.