ERMA Digital pH-601 pH controller offers continuous and accurate pH reading. It also offers alarm when pH reading is out of the user preset range.The alarm feature can be set for either high or low position. Four LED digital display, a wide range of test and control, with high precision and accuracy. Equipped with a high-performance detection electrodes, longterm monitoring and control of water and the pH value. AC voltage, 110V ~ 240V is optional. There are two kinds of tests and test and control function selection. This product has a long-term test pH value of the aquarium, etc.