Review on VIVOSUN Digital PH Meter Tester Pen - High Accuracy 0.01 Water Quality 🌿 Tester with 0-14 PH Measurement Range for Household Drinking, Pool, Aquarium - ATC, Army Green by Conrad Greene

Following the instructions that came with it, I was unable to calibrate this meter at all. Just get the same 4pm no matter what. Holding the calibrate button does nothing other than flash the screen, not calibrate as the instructions say. I tried for over an hour using the instructions and the calibration bags and distilled water provided. Nothing. It's not even worth my time to try and send back. Save yourself the headache, money and most importantly your time and look elsewhere. I took a hit, you don't have to. Zero stars if I could.