I've been using a refractometer calibrated with 35ppt calibration solution and showed my tank running a hair below 35ppt. Yesterday, I purchased a Hanna Salinity Tester (for easier reading). I calibrated it per instructions using the Hanna 35 ppt solutions. When I tested the tank, the reading was 31.8 ppt. I was a bit shocked.
I calibrated the Hanna again and tested- Same results.
I calibrated the refractometer with deionized water to 0 - no adjustment was needed.
I checked the refractometer solution and was bang on 35 ppt. Header scratcher.
I calibrated the Hanna again and no change to the results.
The difference between the Hanna and the refractometer is outside the accuracy listed for the Hanna. Any ideas on how to determine the difference?
I calibrated the Hanna again and tested- Same results.
I calibrated the refractometer with deionized water to 0 - no adjustment was needed.
I checked the refractometer solution and was bang on 35 ppt. Header scratcher.
I calibrated the Hanna again and no change to the results.
The difference between the Hanna and the refractometer is outside the accuracy listed for the Hanna. Any ideas on how to determine the difference?