Salinity Calibration Problems

[Ted_C]

Hi All.

I seem to be having some issues calibrating my salinity probe. I've repeated this process three times now and have been getting the same result with 3 separate 53 ms solutions.

I do have the PM2 module w/ a salinity probe that is approx 2 years old and a temperature probe.

The probe was dry for about a year - as I took a break from the hobby. I have attempted the calibration when first wet (maybe a day of running in water), after a week running in water, and two weeks running in water.

The solutions I've been testing are:
1 foil pack of the 53 ms Neptune solution
1 Pinpoint 53 ms Solution that measures to 35 PPT on the VeeGee Refractometer
Another pinpoint 53 ms solution that also measures to 35 PPT on the VeeGee

My settings when calibrating are
Salinity
Temp Comp: 2.0

When I calibrate with the 53 ms solutions - the same thing happens:
I rinse the probe with RODI water
Let it dry
Calibrate to zero - the probe reads -0016 after it stablizes
Calibrate to the 53000 solution
The probe reads 0625

After accepting the value and examining the main screen - my salinity reads around 9.2 - while it is still in the 53ms standard solution.

Any ideas to try or is the probe junk at this point?

 

[Ted_C]

Screen Shot:

 

[Frozenguy]

1) Are you floating your calibration solution next to the temp probe and allowing the salinity probe to come up to temp before wet calibration?

2) when you say it reads 9.2, is that in Salinity mode? I'm pretty sure that reads in PPT, not ms. So 9.2 shouldn't be 53. However I think 34-35ppt is what it should read for a reef.

3) you say your temp coefficient is 2.0 but your screenshot says 2.2. It should be 2.2, make sure it is.

4) you say you calibrated to zero, then to 53 ms solution. What do you mean you calibrated to zero?

 

[Ted_C]

issue resolved.

For those happening on this thread - my temp probe that was connected to the PM2 module was disabled - either through the upgrade or by default or was disabled last year and the setting stuck through the reset / upgrade.

It was either this or the reboot this morning that allowed me to successfully calibrate.

The temp probe connected to the PM2 appears to be required to be enabled for a proper salinity reading. I calibrated this morning with 35 PPT (53 ms/cm2) with a conductivity compensation of 2.0 with the temp probe connected to the PM2 enabled. Dry (zero) reading was again -0016 and the 53 ms/cm2 solution read 0603. After accepting the value and leaving the probe in the standard solution, the conductivity read 34.8 PPT. The tank reads 33.8 PPT - which is pretty much spot on to the 34 PPT I keep the tank at.

 

[Frozenguy]

You said 2.0 again for temp coefficient. It should be 2.2.

Glad to figured that bug out

 

[Ted_C]

Neptune says to start at 2.0 so that's what I used.

 

[Frozenguy]

That's not what I've been reading from Neptune:

Seawater typically has a temperature correction factor of 2.1 to
2.3 %/C.

Neptune PM2 manual
https://www.neptunesystems.com/downloads/docs/PM2_manual.pdf