Four Salinity Testers, Four DIFFERENT results - Which do you trust?

[Euphylliaphyle]

I would add to that:
Perform 3-4 successive tests on the same sample each time you test, at least for a while, then do that occasionally ongoing to keep things honest. This will help identify test-to-test inconsistencies in the operator-device system. Learn from such inconsistencies, e.g., Did bubbles on the device cause it? - then remidiate the procedure accordingly. This is not exactly a full measurement system analysis, but imo will get to the heart of what we need as aquarists from our salinity measurements.
I was able to get pretty consistent results from my IO swing arm, but it was a bit finicky (swing arm bubble entrapment) and I much prefer the TM glass precision hydrometer.

I wonder if I'd kept my swing arm rinsed clean (vs allowing sw residue to buildup) if the issues with it would have been less? (I may dig mine out and mess around with it someday soon.)

It would not hurt! Btw, you should rinse the salt water off of any hydrometer before storing. Even tap water is better than leaving it there, but RO/DI is better.

 

[fandaga]

I have the Tropic Marin hydrometer, and it’s the most reliable of the 3 testers that I use. I generally use the Hanna salinity checker (conductivity) though because of ease of use.

 

[KrisReef]

Lol

Perhaps you have just been buying cheap “junk”. The modern salinity scale is actually defined in terms of conductivity, not density or specific gravity. Why? Because high quality conductivity meters are highly accurate and more user friendly than hydrometers.

Ahhh, maybe.
How many dollars does a hobbyist have to spend to get a “High Quality “ conductivity meter?

I know that they used to be fairly expensive but I have not checked pricing in a few decades and I don’t know if they are reasonably priced for a hobbyist to get one vs the floating glass hydrometer.??

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Someone else mentioned earlier that a hydrometer can’t be calibrated. I have calibrated a plastic swing arm hydrometer by adding a tiny bit of glue to the arm to increase its displacement and make it ride higher in the water. I would not say that it was pretty but I did make it read properly.


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