A salt system works when the water temperature is above 52 degrees. Before the pool reaches that temperature another form of chlorine would need to be used. Most of our pool owners who do have salt systems have not yet started heating their pool for the year, but once the air temperature reaches its peak in the summer, the salt system is on and producing chlorine whenever the equipment system is turned on.See page 18 for reference: http://www.pentairpool.com/