I've finally figured out how to calibrate it. inadvertently. The first attempt I tried with the leaflet, which I spent too much time on, was unsuccessful. Sometimes it was possible to calibrate it with two solutions but not with the third. I finally gave up, but before putting everything away, I poured some 6.86 solution into the lidβjust enough to soak the bottom of the meter. - and held it so that it stood at the end of the lid. The next day I was ready to put in another portion of the time but it calibrated well. Or at least it seemed so. 6.86, 4.01 and 9.18 are all recorded on the meter when immersed in buffer solutions. But when I tried to take measurements a little later, they were all wrong for every solution. They weren't ridiculous, mostly within 1/10 and 4/10 of a unit, but if you buy a pH meter you probably know that the difference in pH unit is 10 times the difference in concentration. A pH difference of 4/10 is a disaster.
Digital PH Meter Tester - Tiaoyeer Water Quality Tester With ATC, 0.01PH High Accuracy, 0.00-14.00 Measurement Range, 0.01 Resolution For Drinking Water, Aquarium, Swimming Pools, Hydroponic
8 Review
Portable digital multimeter with sound continuity and thermocouple (electric tester) LTX DT-838
7 Review
TDS water quality tester - TDS water hardness meter (portable digital salt meter for water analysis)
9 Review
80 Pieces Water Test Litmus Strips Litmus ph Paper Soil Acidity Meter Liquid pH Tester 1-14
10 Review