Extremely frustrated by the salinty measuring tools available. Does anyone REALLY know what their salinity level are?

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IslandLifeReef

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So the salinity being off by 1 or 2 points doesn't matter? This is a surprising answer to be honest. I always figured to have the best chance of success you really need to have a stable/accurate salinity in the tank. When you mention that constant proportions of seawater don't apply in aquariums, why is that?
@Ari Almassi, I do think that we all can get caught up in the weeds a bit and try to control parameters too much. Have you ever snorkeled or dived on the reefs on the Big Island of Hawaii? If you ever do, you will notice that there is an abundance of fresh water coming from the lava rock beneath the reef from rain run-off. The salinity difference is so great, you can see the fresh water vs the salt water. Even in that environment, there are corals that are flourishing and tons of fish. So, I don't think your inhabitants will care too much if your salinity is 34 ppt or 36 ppt. As long as it stays consistent, which it should with an ATO, you will be fine.
 
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iggy

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Funny how this is trying to make a joke about "purists" or something but in actuality I'm talking about how I'm trying to find an accurate tool in the digital age. I'm not an old man trying to saying that we need to go back to the carburetor. I'm saying that the quality leaves a lot to be desired.
I have struggled with this in the past. In this case digital readings are less accurate for hobby grade equipment. I was not thrilled with the rebranded 35 usd refractomers either.

I settled on the VeeGee STX-3 refractometer. It is much clearer and easier to read. I do find value in some Hanna digital meters but definately not touching digital salinity meters. again They last a year and are innaccurate but get glowing reviews.


https://www.veegee.com/products/handheld-salinity-refractometer

A bright incandenscent bulb in a utility room is needed to get a good reading.


https://aquacraft.net/products-page-2/equipment/refractometer-laboratory-standard/

Salinity standard are suspect as well! I have had luck with this one!

Topic of stability only matters for SPS tanks in all likelyhood. I have seen some cray tanks from 90s for soft corals with no clue what they were doing.
 
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ReefRondo

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I started with a fluval plastic swing arm, then got a very cheap and terrible refractometer, better refractometer, better refractometer, digital milwaukee refractometer and just this week the hanna salinity checker. All have their issues but this new hanna one wins for me so far purely for ease of use. Calibrate, stick it in the sample, done. Will of course update if I find issues.
 

snorklr

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with all the talk about salinity lately i decided not to trust my 90's instant ocean swingarm...so i bought the tropic marin hydrometer...when it read 1.0245 my swingarm was 1.0244... paul b took his swingarm diving with him and just put a sharpie mark at the salinity where he was...
 

Laith

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You are not supposed to put them in the tank, you are supposed to take Aquarium water, pour it into some tall vessel like a graduated cylinder, and put the hydrometer in there, take the reading, then pour the water back into the tank

Exactly. I use the hydrometer every once in a while just to double check that my Hanna is reading more or less correctly. Used correctly, a well calibrated hydrometer gives the most reliable results because it uses basic physics to give you a reading.
 
Fritz

Kris 2020

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I like Refractometers


They are temperature sensitive, so Milwaukee and I assume hanna use more water than the one I linked, so you have to wait for the sample to come to temp equilibrium with the instrument. (the instrument compensates for temp at the instrument temp, not the water sample temp.)
A drop on the vee gee comes to temp immediately.
Use rodi to check zero every month.
I have this same refractometer. I also have 3 different calibration solutions that read the same. I calibrate it once or twice a month, using different solutions to make sure. This refractometer is so much better than my brs one was. I rarely have to adjust it. With the brs one I calibrated every time I used it and often had to make adjustments.
 

Michael E.

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This was my obsession last month. I had an ice cap salinity stick. The first gen. It would read 1.29 on 1.026 water. So, I was running a system with low salt. It was frustrating to find out. Once I did, I went down the rabbit hole of salinity. I Tested multiple standards, refractometers, etc. they were all slightly off. It was hard to find consistency.
I ended up settling on a Hanna conductivity meter. Going off of mS/cm was easier for me. It also satisfied that OCD side. I’ve tested it against an Orion setup we have at work, and it is right there with it . I’ve also been pretty
Lucky to be able to get my hands on some pretty reliable standards that I can reference.
B20273A0-5AF1-4BD8-82AC-65D9A98C22C6.jpeg

Otherwise, I just try to focus on keeping everything stable and consistent.

good luck!
 

Stellar Aquatics

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Whichever you select, take it to a lfs and have them test it more than once. I use the swing arm hydrometer over a year, had them test it 1.025 reads 1.023, I put a mark where I wanted it to be, and It reads the same every time. Doesn't need calibrated, just dip it and rinse for next time.
 

gbroadbridge

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I have tried The Hannah salinity tester (actually I have 2 of them), the brs refractometer, my lfs refractometer. I can't find a tool that makes me feel 100% confident in my salinity. The drift that I have from my Hannah is absurd. After 3 days of use and another calibration my salinity was apparently 4 points higher than what it had originally told me was 35 ppt. I honestly would calibrate the meter every time I used it if it didn't cost $1 per packet of calibration fluid! The refractometers need to be backlit by the sun and the line value changes based on what angle you are looking through it.

Then there is that Milwaukee Instruments meter with amazing reviews, but the issue is that it only has a resolution of 1ppt and an error of +/- 2 ppt! How do you know if your salinity isn't 33 or 37 ppt? How does it have such amazing reviews when your salinity could in actuality be between a range of 33-37 ppt?

Glass hydrometers are a pain because I'd have to completely turn off all my flow every time I want to check salinity.

My desperation is making me look into industrial solutions. I found a $500 industrial salinity meter at Grainger that I might have to suck up and buy. It's so difficult to measure one of the most fundamental parts of this hobby. We have tools for flow, Par, and everything else. No one has been able to make a salinity meter that actually works and you can be completely confident in.

Does anyone have thoughts on this? How do you measure the salinity for your tank? How do public aquariums and food manufacturing facilities measure the salinity of their water? That's what I want. Confidence I can put money on. In this case, its thousands of dollars of quarantined fish and coral.

Grainger meter
A 100ml volumetric flash, an accurate scale, and an accurate thermometer works.

Consistent measurement technique is more important than the absolute value anyway
 
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