... /TDS Meter, etc.PHscan Series Waterproof Pocket pH TesterPHscan series waterproof pocket pH tester include three models (PHscan10, 20, 30), The ... :PHscan series with 2 points calibration function, it will prompt pH calibration point when you calibrate the meter.You need only ... immerse the pH electrode into standard buffer solution and press ENTER key, then ...