Hands-free monitoring and dosing of solution pH levels. The Bluelab pH controller automatically monitors and fine-tunes the pH levels for you. You simply set it, and forget. The pH is taken care of. For use with reservoirs up to 200 gal/760 L. Plant-safe green back lit LCD with adjustable brightness and large, easy to read display. Easy to navigate menu to program, adjust settings and calibration by a simple push of a button. Flashing high/low alarm with control lockouts to protect from over-dosing. Auto resume dosing on restart after power loss. Use with undiluted Bluelab pH Up or Down. 6 month guarantee for Bluelab pH Probe.