Salinity test variance (Apex vs. Hanna)

Spar · Jun 19, 2019

I have the new model of Apex that has the salinity probe. I also have the new Hanna salinity tester (HI98319). Both were just calibrated.
Hanna = 1.024
Apex = 1.022

Should I generally trust the Hanna tester over the Apex? Seems like a large variance.

road_runner · Jun 19, 2019

Spar said:
I have the new model of Apex that has the salinity probe. I also have the new Hanna salinity tester (HI98319). Both were just calibrated.
Hanna = 1.024
Apex = 1.022

Should I generally trust the Hanna tester over the Apex? Seems like a large variance.

I would not trust either if you are looking at 2ppt diffrence.
I would verify with well calibrated refractometer withen the temp range that the refractometer is spec'ed for.
The range you seek is too narrow for both in my openion.

Spar · Jun 19, 2019

Ohashimz said:
I would not trust either if you are looking at 2ppt diffrence.
I would verify with well calibrated refractometer withen the temp range that the refractometer is spec'ed for.
The range you seek is too narrow for both in my openion.

Fair point. I have not tested it against a manual refractometer yet. I should do that. I will also re-calibrate both out of the chance that something screwed up in that process.

road_runner · Jun 19, 2019

Spar said:
Fair point. I have not tested it against a manual refractometer yet. I should do that. I will also re-calibrate both out of the chance that something screwed up in that process.

I am very picky and paranoid with salinity. Pretty much have all the testing tools and I can tell you this, salinity measurements tools can widly vary unless its calibrated withen their spec'ed temperature during the calibration...
Also a role of thumb electrical probs especially cheap ones will drift in time. I advice against depending on them as an absolut measurments rather events triggers..

Spar · Jun 21, 2019

I tested with a refractometer; the problem here is that it obviously needed to be calibrated. I had 3 different brands of 1.026 calibration fluid, and the refractometer read differently on all 3. I assume the risk with those is evaporation driving up the salinity. So I sided with the calibration fluid that was reading the lowest.

I have a Milwaukee salinity tester also that read very differently. So I literally have like 5 different answers to what my salinity might be. Anywhere from 1.022 to 1.025.

What is the most absolute way to know for sure? Seems like if everything is relying on different calibration fluids and still giving different answers afterward, then there is no absolute way... stressful!