Review on 📊 High-Precision Digital PH Meter for Accurate Testing: Pocket-Sized Water Quality Tester, PH Range 0-14, Ideal for Drinking Water, Aquariums, Swimming Pools, Hydroponics by Trevor French

Calibration was difficult at first. And there was only one of each calibration powder, so if you messed up, you'll have to back-order the powder. I wish they had some bags of calibration powder with them. This takes a few seconds longer than expected and you must hold the meter completely still to get a stable reading. When I calibrated mine it took me 3 or 4 tries because my gauge didn't calibrate to the 3rd cup (9.18ph). it just kept flashing 6.86. so I kept restarting. I finally calibrated it but don't know if I can trust the calibration and I can't calibrate it again because I only received one from each pack. Hope it works. I used Kirkland brand water to calibrate but even though it's distilled it says minerals have been added. I'm not sure if this affects the pH of the distilled water.