Consider the following features:
+
Auto-calibration for at least 2 pH points i.e. for calibration using pH
buffer 4.0 and pH buffer 7.0.
+ Double
junction electrode - These are ideal for measuring highly contaminated
samples such as hydroponic nutrient solutions. Cheaper pocket sized pH
meter often feature “single junction electrodes”. These typically fail
very quickly due to chemical attack on the single junction pH reference
electrode system.
+
Combined
millivolt and
pH readout.
+
Readability to pH 0.1. Note that readability to 0.01 is simply
un-necessary for hydroponics. Further, accuracy to 0.01 is rarely
achievable even when meters are properly maintained.
+
Replaceable electrode – this is usually the part that limits the life-span
of any electronic pH meter. When the electrode is not properly maintained
do not expect it to survive more than a few months.
+
Simultaneous pH and temperature display – monitoring and maintaining
nutrient temperature is important for obtaining optimum root performance.
+ Housing
that is both waterproof and floats – helps protect against mishandling.
+ Automatic
temperature compensation – typically standard on most meters.
+ Long
battery life - with auto-off feature to prolong battery life.
