Hello,
I have been running a complete set of profilux 4 since 2.5 years ago.
The temp., orp and pH readings have been very accurate comparing with those with industrial instruments.
I have had some difficulties with salinity measurement from the begining due to electrcal noise resulting unstable readings.
I tried to segregate the cable, adding toroidal ferrite cores etc. It was somting improved, but not so perfect.
Recently, the readings had step changed within couple of ten seconds, several ten minutes or couple of days like,
0.1, 30.5, 0.5, 28.5, 34.0, 28.2 ppt whille greisinger GMH3451 reads very stable 33.9~34.0 ppt.
Finally it stopped at 0.1 ppt all the way long.
I tried to clean the prove with vinigar and citric acid, but the result dosen't change.
As far as I understand, probes at their end of life, usually their output go down gradually and eventually go out of calibration range.
Is this also a phnomenon one of those shown at the end of life of conductivity probes?
I'm concerned about the input circitary of Profilux 4.
Before I buy an expensive new probe, I'd like to check the reason, probe or circuits in Profilux 4.
However, the Profilux salinity readings are not so essential to me, as actual salinity is very stable and I measure with GMH once a week.
Any help would be appreciated.
Son
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