Issue with Salinity Expansion/Probe

hsolano · Post by **hsolano** » Wed Jan 08, 2014 6:56 pm

I have been having issues with my salinity probe readings. I initially calibrated with 35ppt solution used for refractometers. The value from the calibration screen was ~30ppt. Then I placed the probe in my tank and it read 20ppt and it has been decreasing steadily. I have cross checked salinity with 2 separate refractometers, one of them temperature compensating, and I have 36ppt. Heck, I even used the floating needle type and it was in the 36 neighborhood.

Thinking it was maybe temperature related I tuned on the temperature compensation function and re-calibrated, but same results. Anyone have any idea about this or has run into the same issue?

Any help is gladly appreciated!

P.S.: My first post, so please be gentle...

Hugo

rimai · Post by **rimai** » Wed Jan 08, 2014 8:12 pm

Can you place it in a cup of tank water, calibrate and leave it there for a few days?

hsolano · Post by **hsolano** » Fri Jan 10, 2014 2:57 pm

OK, I was scanning on the forums and ran into someone that said micro-bubbles may affect salinity readings, so I moved to the pump side of the sump, away from the skimmer and it is holding at 30 ppt, however, my salinity is 35ppt, not 30. Anything else I should be checking?

rimai · Post by **rimai** » Fri Jan 10, 2014 3:18 pm

Try recalibrating with the probe in the tank.
Your solution may not be good for electronic meters.
Remember that we are measuring conductivity and not light refraction.

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