● A calibration facility requiring two pH buffers is essential i.e. uses pH buffer 4.0 and pH buffer 7.0 for calibration.
● Readability to pH 0.1: Readability to 0.01 is un-necessary for nutrient solutions. Further, accuracy to 0.01 is rarely achievable even when meters are properly maintained.
● Combined millivolt and pH readout.
● Replaceable electrode: This is the component that usually limits the life-span of an electronic pH meter.
● Waterproof housing is desirable.
● Automatic temperature compensation: Standard on most meters.
● Auto-off feature: For prolonging battery life.
PH MEASUREMENT & CONTROL: pH meter maintenance and accuracy problems | Measuring pH with 'indicators'