Hanna Instruments portable meter for water chemistry together with depth, one model.
HI98195
This Hanna Instruments portable meter measures water chemistry together with depth, from pressure.
A lake is not one water. Temperature, oxygen and conductivity stratify with depth, and a reading without a depth is a reading you cannot repeat. Adding pressure turns a set of numbers into a profile.
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.
Lower the probe slowly and let each depth settle; a fast descent gives a smeared profile that reads like stratification but is not.
Supplied as one model.