I quote only this statement, because it seems too difficult to quote multiple statements:
[quote=”Stefanie” post=3154][…] How can this be if “it violates some electrochemical laws”?[/quote]
It generally is an error of measurement, not passing a criticism on someone. I’ve calibrated dozens of pH-meters several times, and if you ever find two ore more pH-meters which show the same values of a water solution though carefully calibrated before I will congratulate you.
One pH-step increases the acid concentration to the power of ten, this is significant especially at lower pH-values. If your measured values do not conform, it’s an error of measurement.
I’ve appended a more detailed view of pH and corresponding EC, if youe measure a lower value of EC at a given pH, your given equipment, either the pH-meter or the conductometer, went wrong.