Embodiments of the invention provide a method of regenerating a capacity of a flow-through capacitor. A target value for a water property concentration in a discharge water stream exiting the flow-through capacitor is established. A feed value for the water property concentration in a feed water stream entering the flow-through capacitor is measured. An amount of the water property concentration to be added to the feed water stream is calculated based on the feed value to achieve the target value for the water property concentration in the discharge water stream. An amperage of the flow-through capacitor and a flow rate through the flow-through capacitor is controlled to add ions to the feed water stream to achieve the target value for the water property concentration in the discharge water stream. In some embodiments, the amperage can be set and the flow rate controlled to achieve the target concentration.