The Milwaukee Instruments pH Monitor, SMS120 allows you to continuously monitor pH values in your aquarium.Features:Visual LED alarm when values go above a user selectable set point; and 2 point manual calibrationMeter is powered by a 12 VDC adapter (included)Comes complete with electrode and 20 mL 7.01 calibration solution. You may wish to purchase extra pH calibration solutionProduct Manual (pdf file in new window)