Chemtrol® PC2100 Programmable Controller, 110/230V. The Chemtrol® PC2100 is a simple and reliable programmable controllers that features automatic maintenance of water chemistry, pH and ORP (optional: free chlorine sensor with direct reading in PPM or mg/l) with acid or base feed, programmable super-chlorination and chemicals savings cycles and display of the Langelier Saturation Index. The main screen on the 8-line display enables the operator to supervise all process functions at a glance and to quickly respond to any changing condition. The Chemtrol® PC2100 controller operates like a computer with multi-line screen displays and direct access to all menus and submenus. The front panel keypad is used to move up and down each menu and enter or exit the submenus. All operating functions can be easily modified from the keypad, including sensor calibration, control setpoints, alarm levels and the programs for superchlorination and chemical savings.