The hardness setting just allows it to adjust for how often it will recharge. The higher the number/setting, the oftener it will recharge. The resin bed will handle a certain flow of water and will remove hardness until the bed needs recharging. If it feels soft after recharging and then gets worse later, then you need to recharge more often. If it never feels soft then you have other problems and maybe your unit is undersized for the water volume/hardness.