Review on FOMOOUR pH Meter - High Accuracy Water Quality Tester - 0.01 pH Measurement Range - Ideal for Water, Brewing, Food, Soil, Sauce, and Laboratory Testing - Includes TDS Meter and pH Pen by Moises Dzihic

I bought this pH pen to test a hydroponic solution for my garden. Delivery time was fast. The packaging was good. The pen is NOT properly calibrated. I don't even have the option to calibrate it with the 3 solutions provided. It's like he doesn't even have a calibration setting for 9. He only calibrates with 4 and 6. I've read the instructions and bought many Ph pens over time. Operating errors are therefore not a problem. After it's calibrated (with 4 and 6 only) I tested it with another brand I have and with a batter kit. The pin deviated by at least 1.1 on each test. I checked it 3 times each time. against my other pen and batter set. Each time this pin was somewhere between 0.5 ph and 1.1 ph. I used the calibration solution provided AND the solution I ordered (in case I received a bad batch of solution mix). Get the Vivosun brand or any other popular brand. All this with a brand new pen straight out of the box!