This microprocessor-based ion concentration controller is perfect for in-line batch processing, control processing, or water treatment for various ions like ammonia, ammonium, calcium, chloride, fluoride, lead, nitrate, potassium, silver/sulfide, sodium, or water hardness, etc. (order electrodes separately). This controller continuously displays current ion reading with relay status. Relays are triggered when current concentration reaches high or low setpoints. Its analog output 0/4 to 20mA allows connection to a printer, datalogger, or computer for a continuous record of readings and alarm conditions.