Now take a more authentic meal and send batteries, waterproof written PH meter, using a highly sensitive chip, 140 yuan for the accuracy 0.1PH meter (about 30 seconds stable reaction, mostly for farming, particularly the use of high accuracy is not required), 180 yuan for the accuracy 0.02PH meter (reaction 2 minutes or so stable, with the majority of laboratories, and some require a relatively high detection precision use)