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Twincam
04.01.2011, 16:05
Conductivity Reading Dropping

I have just updated to the latest version of the firmware 5.05 on my Profilux Plus 2 and recalibrated the PH and conductivity probes.
I am having the following problem with the conductivity probe.
The calibration was ok

Air ADC 18
53Ms ADC 408

When checked after the results were 0.1Ms and 52.9Ms so calibration was ok

When the probe is placed in the sump it initially reads correctly at 53Ms (also checked with refractometer) then over 30 minutes or less the reading goes down to about 51Ms

I have read threads concerning electromagnetic fields that are sent out by equipment in the sump and to eliminate this factor (if it exists) I removed the probe from the sump and placed it in a glass full of sump water and left it to stabilise. It initially read 53Ms then started to reduce as previous.

During this test the glass was insulated to avoid temp drop and isolated from the sump pumps. Also the contacts on the probe had been cleaned prior to calibration.

The nearest un-isolated pumps were Eheims on my skimmer (not in sump) at about 1.75 mts – is this too close?
Can the electromagnetic field be picked up by the cable as well as the electrodes?

Yours advise would be appreciated

Harold

GHL Support
05.01.2011, 10:01
To be sure that the pumps don't cause the dropping value you could take the pumps out of your tank and put them more far away ... we have also had a customer who had
a moor radix in his tank which had caused deviations in the conductivity measurement.