A sensor system and process that utilizes impedance/conductivity measurements to track the movement of hardness in an ion exchange media. The impedance/conductivity sensor is a vertical, longitudinally directed, axially lengthwise electrode system having electrodes placed within a bed of ion exchange material and separated by water and the ion exchange material. The electrodes generally run parallel to one another. Hard water is introduced to the water softener and softened by the ion exchange material. A hardness gradient is tracked by the sensor, and regeneration is initiated when it is determined that the ion exchange material is depleted or exhausted.