Pro-matic ESC 24 salt chlorinator. Two red lights on the control box. My pool engineer says that the salt system is defective because I turned off the system during the winter season but did not bypass the cell so pool water continued top flow through it. Is this correct ? He also said that I should not be supplementing the chlorine in the pool when it is low due to sudden bather load etc with sodium hypochlorite. "A salt system does not need additional chlorine".