Ion exchange filters are really helpful in water softening.
For example, WaterBoss softeners remove hardness salts up to 24 mg/l, and WaterMax — up to 38 mg/l. Moreover, WaterBoss filters remove iron and manganese from water. WaterMax also handles nitrates and high molecular weight organic compounds. Compared to other softeners, these systems remove impurities more thoroughly and use significantly less water and salt for resin recovery.
See catalogue of softeners.