Hanna Instruments portable meter for a full water quality profile from a single probe, one model.
HI9829
This Hanna Instruments portable meter measures a full water quality profile from a single probe, with position logged.
On a survey the hard part is not measuring but knowing where each measurement came from. A meter that stamps every reading with a GPS position turns a day of sampling into a map, and removes the notebook step where locations get transposed.
An electrochemical meter is three things that fail separately: the electrode, which ages and eventually dies; the meter, which rarely goes wrong; and the calibration, which is only as recent as the last time somebody did it. Almost every bad reading traces to the first or the third.
Budget for electrodes as consumables, store them wet in storage solution rather than water, and calibrate against fresh buffers at the temperature you will measure at.
The multi-sensor probe is the expensive part of the system; specify the cable length you actually need, because it is not changed later.
Supplied as one model.