Hanna Salinity checker confusing results!

[AlexandraDreadlocksPanda]

So I’ve got some results here that I just can’t fathom.
I calibrate my Hanna salinity checker with the Hanna calibration sachets. It reads 35ppt.
Check my Reef tank, it reads 35ppt. I checked it at the same time as I took water samples for Triton ICP, and that came back as 36.047 PSU.
How does that work then? I’m really confused!

 

[BryanM]

@Randy Holmes-Farley may have some insight here.

 

[mook1178]

The precision of your meter is +/- 1ppt. That means your actual salinity is somewhere between 34-36. So the ICP and Hanna agree.

 

[W31Olds]

Not an issue you can correct. I checked my Hanna against my TropicMarin Hydrometer yesterday and it reads almost 2 full ppt low. I don't even bother to Calibrate it anymore, just check it against the Standard and compensate for the difference. It does always read consistently low.

 

[AlexandraDreadlocksPanda]

The precision of your meter is +/- 1ppt. That means your actual salinity is somewhere between 34-36. So the ICP and Hanna agree.

If that were the case, it wouldn’t be reading exactly right with a reference solution though, would it? Also stated accuracy for Hanna checker is 0.2ppt..

 

[winxp_man]

I’m finding that calibrating the Hanna checker for me got it read correctly against my Tropic Marin Hydrometer by acclimating the calibration solution pack in the tank first to the temp the tank is at. Been 4 months since, and still reads correctly when I test it on a regular.

 

[EnterName]

The Hanna salinity meter can operate quite accurate but its calibration process isn't as straight forward as one might think:

Before calibrating I recommend letting it sit in acetic acid (up to 20%) or dilute hydrochloric acid (a few % are probably enough) for a few minutes. This will clean the electrodes and can significantly help with stabilizing readings. It might also be possible to use very fine sanding paper on the carbon electrode, but I didn't try it yet.

Afterwards you wash the probe with RO/DI or distilled water and let it dry.

You need to make sure the calibration solution is as close as possible to 25°C/77°F as the used temperature compensation algorithm doesn't seem to work very well during calibration. I usually let the solution sit somewhere in my tank for a few minutes to get it to temperature. You can also use Randy's calibration standard (the conductivity standard at the end of the article), but you will still need to get it to temperature.

However, as was already mentioned, the salinity meter has a certain margin of error and you won't be able to fully get rid of that.

 

[Jamie9]

Mine consistently reads a bit low when compared to my LFS. I’m generally more concerned with making sure my water changes are the same or very close to the salinity in the tank, and it’s at least very consistent in its readings so that sort of works for me. I just need to remember to account for that if say, I’ve got a fish coming in that has been used to low salinity. That said, I’m going to try the acetic acid technique above and see what that does for me.

 

[KStatefan]

If that were the case, it wouldn’t be reading exactly right with a reference solution though, would it? Also stated accuracy for Hanna checker is 0.2ppt..

The spec on the Hanna HI98319U is +-1 ppt for the range you are testing. What meter do you have? My Hanna consistently reads about 1 ppt lower then what I test with a hydrometer. I do not know how Triton measures/calculates salinity but I would not worry about that difference.

 

[BubbleAlgaeFarmer]

Don't worry guys, i have your solution. Once you go refractometer, you'll never go back! I hated them at first but as it turned out, buying a crap refractometer gets crap results. I have the Sybon and it's a tank and has yet to be out of calibration. It just works

 

[AlexandraDreadlocksPanda]

The spec on the Hanna HI98319U is +-1 ppt for the range you are testing. What meter do you have? My Hanna consistently reads about 1 ppt lower then what I test with a hydrometer. I do not know how Triton measures/calculates salinity but I would not worry about that difference.

I’m using Hanna Hi-98319. As I stated earlier, quoted accuracy is 0.2ppt. Specs are right here…
https://www.hannainstruments.co.uk/aquarium/2578-hi-98319-waterproof-salinity-tester

 

[KStatefan]

I’m using Hanna Hi-98319. As I stated earlier, quoted accuracy is 0.2ppt. Specs are right here…
https://www.hannainstruments.co.uk/aquarium/2578-hi-98319-waterproof-salinity-tester

for the low range which is 0.00 to 10.00 ppt.

I did not see that you has listed which one you were using.