Salinity Differences

[peterneish]

Hi all,

I'm currently in the midst of a bit of confusion in relation to salinity within my tank.

I use the Hanna salinity tester and of late, after much neglect, readings in my tank were a little low, around 32.5 ppt. I turned off my ATO in order to bring the salinity back up slowly to give me a current reading of around 35 ppt using the Hanna.

I took a sample of my water to my LFS today to get them to test it. They advised that the reading on their digital refractometer was around 37 ppt, not the 35 as given using the Hanna.

Once I got home I calibrated my Hanna tester and tested my tank again. Same result, around 35 ppt. I then tested the Hanna calibration solution, which gave a reading of 34.9.

I then tested the salt water which I get from my LFS and it gave a reading on 34.7. Surely, if my Hanna is faulty and reading low, then their salt water is also of a higher salinity?

Is it possible that the higher readings from my LFS are as a result of the drop in temperature of the sample that I collected from my tank? Or simply that their digital refractometer is incorrect and/or has not ben calibrated?

I'm keen to hear some experienced opinions.

Thanks in advance.

Peter

 

[Gtinnel]

Most salinity testers compensate for temperature. It’s possible that their digital refractometer could be off, but it’s also possible that your Hanna checker could be off also.
The easiest way to know is to make your own solution with a known value and check your tester against it. There is an easy recipe around the forum that is made with rodi water and table salt.
My experience with the Hanna salinity pen has not been great so I may be biased.

 

[vetteguy53081]

Agree- temperature plays a role

 

[Randy Holmes-Farley]

Hi all,

I'm currently in the midst of a bit of confusion in relation to salinity within my tank.

I use the Hanna salinity tester and of late, after much neglect, readings in my tank were a little low, around 32.5 ppt. I turned off my ATO in order to bring the salinity back up slowly to give me a current reading of around 35 ppt using the Hanna.

I took a sample of my water to my LFS today to get them to test it. They advised that the reading on their digital refractometer was around 37 ppt, not the 35 as given using the Hanna.

Once I got home I calibrated my Hanna tester and tested my tank again. Same result, around 35 ppt. I then tested the Hanna calibration solution, which gave a reading of 34.9.

I then tested the salt water which I get from my LFS and it gave a reading on 34.7. Surely, if my Hanna is faulty and reading low, then their salt water is also of a higher salinity?

Is it possible that the higher readings from my LFS are as a result of the drop in temperature of the sample that I collected from my tank? Or simply that their digital refractometer is incorrect and/or has not ben calibrated?

I'm keen to hear some experienced opinions.

Thanks in advance.

Peter

Temp should not be an issue for these devices.

I'd also advise that the two ppt range (35-37) is well within expectations for these sorts of devices.

The Hanna claims +/- 1 ppt
Milwaukee digital refractometer 887 claims +/- 2 ppt

Fortunately, reef aquaria have a wide range of acceptable salinity.

 

[X-37B]

This is why I use a TM floater.
Its super easy to use and nothing to calibrate or add. Get a 500ml graduated cylynder to float it in.
Imo, its hard to make a mistake with it.

 

[Randy Holmes-Farley]

Imo, its hard to make a mistake with it.

Except for temp corrections.

 

[X-37B]

Except for temp corrections.

Yes but they are minimal and its easy to use the chart. Most tanks run 77 to 80. The difference is their but its not enough for me to worry about.
The difference of 77 vs 80 is only .0004 difference. 1.0264 vs 1.0268.
This is using the chart. Guess I should see what the calculator say as I have neverr used it.

 

[X-37B]

Calculator gave me the same number.

 

[Salty_Northerner]

Hi all,

I'm currently in the midst of a bit of confusion in relation to salinity within my tank.

I use the Hanna salinity tester and of late, after much neglect, readings in my tank were a little low, around 32.5 ppt. I turned off my ATO in order to bring the salinity back up slowly to give me a current reading of around 35 ppt using the Hanna.

I took a sample of my water to my LFS today to get them to test it. They advised that the reading on their digital refractometer was around 37 ppt, not the 35 as given using the Hanna.

Once I got home I calibrated my Hanna tester and tested my tank again. Same result, around 35 ppt. I then tested the Hanna calibration solution, which gave a reading of 34.9.

I then tested the salt water which I get from my LFS and it gave a reading on 34.7. Surely, if my Hanna is faulty and reading low, then their salt water is also of a higher salinity?

Is it possible that the higher readings from my LFS are as a result of the drop in temperature of the sample that I collected from my tank? Or simply that their digital refractometer is incorrect and/or has not ben calibrated?

I'm keen to hear some experienced opinions.

Thanks in advance.

Peter

Hey Peter, use this calibration fluid and your Hanna tester will be right on the money. Go-to BRS and read some of the reviews. I bought like 20 packs of the Hanna fluid and 2 packs of the Neptune conductivity packs and they are way more accurate. I test it against the Tropic Marin high precision hydrometer and am able to have total faith in the Hanna. Hope this helps ya.

 

[peterneish]

Thanks very much all, really appreciate the input. lots of useful stuff to take away.

 

[peterneish]

Hey Peter, use this calibration fluid and your Hanna tester will be right on the money. Go-to BRS and read some of the reviews. I bought like 20 packs of the Hanna fluid and 2 packs of the Neptune conductivity packs and they are way more accurate. I test it against the Tropic Marin high precision hydrometer and am able to have total faith in the Hanna. Hope this helps ya.

Very helpful. I have order a few packs. Thank you

 

[CABIX_81]

i have pretty much issue also with my salinity,, tank salinity is at 1.020, did a water change (20gal) . I mix 4gal and 1/2cup of salt each a gallon,, before i add it to my tank, i read 1.024, dunp it in and read the same as 1.020. Any advice would help

 

[Randy Holmes-Farley]

i have pretty much issue also with my salinity,, tank salinity is at 1.020, did a water change (20gal) . I mix 4gal and 1/2cup of salt each a gallon,, before i add it to my tank, i read 1.024, dunp it in and read the same as 1.020. Any advice would help

What are you using to measure salinity?

 

[CABIX_81]

What are you using to measure salinity?

Refractometer

What are you using to measure salinity?

 

[Randy Holmes-Farley]

Refractometer

What brand?
How did you calibrate it?

 

[CABIX_81]

What brand?
How did you calibrate it?Hallocool

I calibrate in room temp with distilled water to zero

 

[Randy Holmes-Farley]

I’d recommend a 35 ppt standard, not to/di as it is likely not going to be accurate using ro/di.

That said, I’m not sure what exactly you are having trouble with.

If the specific gravity is 1.020, I’d raise it to 1.026 by replacing evaporated water with seawater until you get there. Water changes are a poor way to adjust salinity.

 

[CABIX_81]

I’d recommend a 35 ppt standard, not to/di as it is likely not going to be accurate using ro/di.

That said, I’m not sure what exactly you are having trouble with.

If the specific gravity is 1.020, I’d raise it to 1.026 by replacing evaporated water with seawater until you get there. Water changes are a poor way to adjust salinity.

Ok Ill try the method of using seawater in the next few days and update here.. much appreciated