A system for controlling the operation of conductive plates immersed in an aqueous solution, such as in water treatment applications. The system allows independent control of the current sourced or sunk by each of a plurality of plates. The system also allows each plate to be placed in a high-impedance state in which no appreciable current is sourced or sunk by the system. A plate or a group of plates is controlled by a control module which interfaces to a central controller such as a personal computer or a programmable logic controller. Multiple control modules can be added to a system to support multiple plates, each of which can be controlled individually from the central controller. Each control module is also capable of sensing voltage and current at its corresponding plate and providing that information to the central controller.