Hanna salinity checker vs apex probe


New member
So my new build just got salt a few days ago, my brand new Hanna salinity checker calibrated with the solution it came with is showing 1.024 and my apex probe also brand new was calibrated with the solution it came with.... it's reading 38.1PPT ( 1.028)

The Hanna matches my refractometer
I will obviously have to buy some more calibration fluid and do both together but curious which way you guys would lean to being more accurate?


New member
i think the probe is out to lunch, I just recalibrated both with 35 PPT solution and they both read 35 PPT now an hour later the probe is back up to 39.8. the hanna checker and the refractometer match each other along with the solution as well.

well thats disappointing for a 2 week old unit


New member
Yea, the apex probe reads high on mine too. I would trust the hanna checker and use the apex probe to monitor large fluctuations in salinity, not accuracy. It is very finicky. And try to keep it away from areas with a lot of flow and micro bubbles. That helped for me as bubbles in the probe throw it off

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Spaced Cowboy

South Bay Reefer
This might be of some use

Note the sensitivity to the temperature during calibration, and the advice to:
  • float the calibration packet in the water adjacent to the temp. probe for 15 minutes prior to calibration
  • Make sure the calibration solution packet remains in the aquarium water during the process

If you've done both of those, feel free to ignore this :)