Greisinger gmh 5530 ph waterproof handheld measuring device for ph redox greisinger gmh 5530 the greisinger gmh 5530 ph is a waterproof handheld measuring device for ph redox designed for measuring ph and orp potentials with the help of adequate electrodes the electrode is connected via bnc socket please note different electrode types are needed for ph and orp measurementsit is possible to connect a temperature probe pt1000 or ntc 10k banana plugs additionally this enables an autom