Chlorine can be fed continuously or as a shock dose. On a shock basis, suffi cient chlorine may be fed to provide a residual
chlorine level up to 1 mg/I free residual chlorine, measured downstream of water cooling systems, for one hour, two to three
times daily. To reduce the chlorine swings and in order to keep the system running consistently, continuous low
chlorine feed is used to keep the residual at about 0.2 to 0.5 mg/I free residual chlorine throughout the system.