Review on Revolutionize Hydroponics with KETIEE Resolution Standard Aquariums by Jeremy Choi

By pressing this calibration button you can mess up the programming so that 4 is no longer mistaken for 4.0. the right liquids, he doesn't get any closer and finds that almost 10 ph is acceptable for calibration - then he sets that number and the unit is now unusable. It should automatically register the 4.0 or 7.0 (6.86) solution, which worked fine before I tried to calibrate - now it's useless. Buy something better. Also, it doesn't stay calibrated for long, whether you wash it or not. Don't count on it for your gardening needs.