Then you probably have water flowing into the salt tank when it shouldn't be. The cause is the brine piston and seals leaking. So you replace the main and brine pistons and seals called the stack. To test that guess remove the brine line from the fitting on the control valve and watch to see if there is water flowing out the fitting after a minute or so. If there is that's your problem and it prevents any water from being sucked out of the salt tank during the Brining position and usually allows flow into the salt tank rather sucking any out.