Not sure which salinity tester is correct

[kiran]

I have one of those Milwaukee salinity testers from brs and also a hanna instruments salinity tester. Both units were calibrated properly before use.

An example is I went to go check the salinity of the saltwater I just made. My Milwaukee is telling me it's at 1.025 but my hanna is telling me that it's 1.023.

I'm not sure which one is correct.

 

[KrisReef]

What’s the error range for each instrument.
I still use a plastic swing arm hydrometer

 

[Gtinnel]

I have and use both of those salinity checkers and for what it's worth I see the same thing with the Hanna showing low, where the Milwaukee matches my optical refractometer and apex salinity probe.
The only way to know for sure is to test them with a solution of known salinity. Randy Holmes Farley has an article about making your own with just rodi water and table salt, which is what I use to verify my salinity testers.
I can find and link the article if you want.

 

[Sean Clark]

I have not tested these two against eachother. I use the Hanna and find that it to be quite accurate. That being said... The accuracy statement by the manufacturer is plus or minus 2psu or 2ppt.

Digital Refractometer for Seawater Analysis

HI96822 is a digital refractometer to measure salinity of seawater with an accuracy of +/- 2 PSU, 2 ppt and 0.002 specific gravity.

www.hannainst.com

The "best" most consistent control is a floating hydrometer.

 

[kiran]

I have and use both of those salinity checkers and for what it's worth I see the same thing with the Hanna showing low, where the Milwaukee matches my optical refractometer and apex salinity probe.
The only way to know for sure is to test them with a solution of known salinity. Randy Holmes Farley has an article about making your own with just rodi water and table salt, which is what I use to verify my salinity testers.
I can find and link the article if you want.

That would be much appreciated. Thank you!

 

[mdb_talon]

Agree with Gtinnel that need to test against know solution to really know the answer. Having said that my bet is on the milwaukee for sure.

 

[kiran]

I have not tested these two against eachother. I use the Hanna and find that it to be quite accurate. That being said... The accuracy statement by the manufacturer is plus or minus 2psu or 2ppt.

Digital Refractometer for Seawater Analysis

HI96822 is a digital refractometer to measure salinity of seawater with an accuracy of +/- 2 PSU, 2 ppt and 0.002 specific gravity.

www.hannainst.com

The "best" most consistent control is a floating hydrometer.

Yeah I think I might just have to pull out the hydrometer and test it against that.

 

[kiran]

Agree with Gtinnel that need to test against know solution to really know the answer. Having said that my bet is on the milwaukee for sure.

The Milwaukee came with it's own solution at 1.025 and it tests correctly every time. The thing is that the Hanna also comes with sachets that are at 35ppt and the Hanna checks that correctly too.

I just saw another post in this thread that says that hanna might test lower.

 

[Sean Clark]

The Milwaukee came with it's own solution at 1.025 and it tests correctly every time. The thing is that the Hanna also comes with sachets that are at 35ppt and the Hanna checks that correctly too.

I just saw another post in this thread that says that hanna might test lower.

Cross check them? I don't have both or I would.

 

[Gtinnel]

That would be much appreciated. Thank you!

It is a very detailed article but if you scroll down it's pretty easy to find the directions. I also scaled up the recipe 10 times to lessen small measuring errors and I used cheap kitchen scales for measuring the weights.

Also, please note the standard for the refractometer (Milwaukee) is not the same as the one for the conductivity pen (Hanna). So to test both you would have to make both standards, but since they cost almost nothing to make it shouldn't be a big deal.

http://reefkeeping.com/issues/2004-06/rhf/index.php

ETA- it was brought up a few posts later that I'm not positive that you're referring to the Hanna conductivity pen. If using the Hanna digital refractometer then it would be the same reference solution as a Milwaukee digital refractometer.

 

[kiran]

It is a very detailed article but if you scroll down it's pretty easy to find the directions. I also scaled up the recipe 10 fold to lessen small measuring errors and I used cheap kitchen scales for measuring the weights.

Also, please note the standard for the refractometer (Milwaukee) is not the same as the one for the conductivity pen (Hanna). So to test both you would have to make both standards, but since they cost almost nothing to make it shouldn't be a big deal.

http://reefkeeping.com/issues/2004-06/rhf/index.php

Thank you for the info!

 

[Gtinnel]

Also my Milwaukee never tested the reference solution that it came with correctly, that is why I started making my own.

 

[gbroadbridge]

I have one of those Milwaukee salinity testers from brs and also a hanna instruments salinity tester. Both units were calibrated properly before use.

An example is I went to go check the salinity of the saltwater I just made. My Milwaukee is telling me it's at 1.025 but my hanna is telling me that it's 1.023.

I'm not sure which one is correct.

Consistency is more important than the exact number.

The milwaukee is +- 0.002 accuracy so seawater at 1.026 could read anything from 1.024 to 1.028.

I have both and when the Hanna says 1.026, the Maiwaukee says 1.028.

As I've calibrated the Hanna against a known standard, it's the one that provides the baseline here.

There is no means to adjust the milwakee and you rely on the factory calibration of the prism.

 

[Sean Clark]

It is a very detailed article but if you scroll down it's pretty easy to find the directions. I also scaled up the recipe 10 fold to lessen small measuring errors and I used cheap kitchen scales for measuring the weights.

Also, please note the standard for the refractometer (Milwaukee) is not the same as the one for the conductivity pen (Hanna). So to test both you would have to make both standards, but since they cost almost nothing to make it shouldn't be a big deal.

http://reefkeeping.com/issues/2004-06/rhf/index.php

I assumed we were talking about the Milwaukee MA887 Digital Seawater Refractometer

And the Hanna HI96822 Digital Refractometer for Seawater Analysis

This is on me if this is not the case.

 

[Gtinnel]

I assumed we were talking about the Milwaukee MA887 Digital Seawater Refractometer

And the Hanna HI96822 Digital Refractometer for Seawater Analysis

This is on me if this is not the case.

Oh, very good point. I was talking about the Milwaukee MA887 and the Hanna HI98319 (conductive pen).
I guess we both took for granted what the OP was referring to and at least one of us was wrong. I never even considered asking what model of each.

 

[Gtinnel]

There is no means to adjust the milwakee and you rely on the factory calibration of the prism.

If talking about the Milwaukee MA887 then it can be calibrated. It just gets calibrated with distilled water.

 

[Sean Clark]

@kiran could you please help us by specifying what tools you are using?

 

[kiran]

@kiran could you please help us by specifying what tools you are using?

Yeah sorry about that. Completely forgot about the models.

Milwaukee MA887

Hanna HI98319

 

[Gtinnel]

Yeah sorry about that. Completely forgot about the models.

Milwaukee M887

Hanna HI98319

Are you sure it's the MA871 and not the MA887. The MA871 is a brix refractometer and not really for saltwater.

 

[kiran]

Are you sure it's the MA871 and not the MA887. The MA871 is a brix refractometer and not really for saltwater.

Yeah it's MA877