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

[Laith]

Just get a floating hydrometer such as the one from Tropic Marin. It is based on simple proven physics, calibrated at the factory and will give you the most accurate salinity reading available. You do need to measure the temp of the water that the hydrometer floats in but I've found that the temp difference doesn't make that much of a huge difference. If you do want to input the water temperature of the water sample, this calculator will give you everything you need:

Salinity calculator

A unit converter for calculating salinity in marine aquariums. The calculator supports conductivity (mS/cm), salinity (PSU og ppt), density (g/cm³) og specific gravity.

reefapp.net

And overall, it is probably one of the cheapest options out there!

 

[Reef.]

Just get a floating hydrometer such as the one from Tropic Marin. It is based on simple proven physics, calibrated at the factory and will give you the most accurate salinity reading available. You do need to measure the temp of the water that the hydrometer floats in but I've found that the temp difference doesn't make that much of a huge difference. If you do want to input the water temperature of the water sample, this calculator will give you everything you need:

Salinity calculator

A unit converter for calculating salinity in marine aquariums. The calculator supports conductivity (mS/cm), salinity (PSU og ppt), density (g/cm³) og specific gravity.

reefapp.net

And overall, it is probably one of the cheapest options out there!

Agree, but a 500ml measuring cylinder too, then you don’t have to turn off flow.

 

[ingchr1]

....If you do want to input the water temperature of the water sample, this calculator will give you everything you need:

Salinity calculator

A unit converter for calculating salinity in marine aquariums. The calculator supports conductivity (mS/cm), salinity (PSU og ppt), density (g/cm³) og specific gravity.

reefapp.net

...

Am I missing something or is this calculator correcting in the wrong direction? Here's a comparison to Hamza.

Also, would I first need to temperature correct the SG then convert that corrected value to get the PSU? The calculator shows PSU the same at both temperatures when entering a SG measurement.

Salinity Correction Calculator

Aquarium calculator; Correct a relative specific gravity (sg) measurement taken with a non-temperature-correcting unit.

www.hamzasreef.com

 

[homer1475]

Does it really matter?

If your measuring device says 1.026, and you use that same device every time, does it really matter if it's 1.024 or 1.028?

I use a hanna meter, calibration packet says 35psu, tank reads 35psu, mixed up water reads 35psu. Does it really matter if it's truly 33 or 38. No I don't think so, since corals can be found in ever "normal" salinity around the world.

At the end of the day, stability matters, not some actual number on a scale.

People are bored and way overthinking the basics these days.

 

[Laith]

Agree, but a 500ml measuring cylinder too, then you don’t have to turn off flow.

Yes, I got the "package" from TM which included the hydrometer and a plastic measuring cylinder.

 

[Laith]

Does it really matter?

If your measuring device says 1.026, and you use that same device every time, does it really matter if it's 1.024 or 1.028?

I use a hanna meter, calibration packet says 35psu, tank reads 35psu, mixed up water reads 35psu. Does it really matter if it's truly 33 or 38. No I don't think so, since corals can be found in ever "normal" salinity around the world.

At the end of the day, stability matters, not some actual number on a scale.

People are bored and way overthinking the basics these days.

When I got the hydrometer and tested, it showed an SG of 1.0285 or 37.9ppt. My calibrated Hanna was showing 1.026 and 35ppt. I still use the Hanna most of the time (quicker), I just look for a ppt of 32 instead of 35.

Yes, I agree that stability is more important.

But in my tank mixing up fresh saltwater to 35ppt instead of almost 38 saves me a not inconsiderable amount of spend on salt: I use 8.9kg of salt for each fresh mix instead of 9.4kg .

It's not huge but it does add up!

 

[Big Smelly fish]

I have an old Milwaukee refractor I’ve been using for the last 20years, I do have some cheap plastyones like instant ocean and the like I compare them from time to time and can say they are way off and I remark with what the refractor reads . So I can do quick checks without getting the refractor out.

 

[Laith]

Am I missing something or is this calculator correcting in the wrong direction? Here's a comparison to Hamza.

Also, would I first need to temperature correct the SG then convert that corrected value to get the PSU? The calculator shows PSU the same at both temperatures when entering a SG measurement.

Salinity Correction Calculator

Aquarium calculator; Correct a relative specific gravity (sg) measurement taken with a non-temperature-correcting unit.

www.hamzasreef.com

Well the SG does go up with the higher temp in the calculator I'm using (your example goes from 1.0251 to 1.0256 at the higher temp). Your example shows it doesn't go up to 1.0261 as the Hamza version shows.

I don't know why though... maybe a slightly different algorithm is used? But that doesn't make sense either.

In my case, my hydrometer measures Density, not SG (which I did not realize for a couple of months!). So I enter a temp of 27C and my density and get the SG/PSU results.

 

[KStatefan]

In my case, my hydrometer measures Density, not SG (which I did not realize for a couple of months!).

That seems to come up once in awhile and some use them interchangeably

 

[flyingscampi]

I use a Hanna probe to measure conductivity, and a D-D seawater refractometer that measures the refractive index. Both devices convert their native measurement to display a salinity reading in ppt. I don't have a hydrometer, so I never use S.G.

I mix a batch of seawater once a month, then heat and circulate it for 24 hours before adjusting the salinity until the Hanna measures 35 ppt (the same as the aquarium). I then check the KH, Ca & Mg on the new mix are within the salt makers published range. For the Tropic Marin Pro Reef salt I use, these are: Alkanity: 7 - 8 KH, Ca: 430 - 450 ppm, Mg: 1300 - 1350 ppm.

I only bother calibrating the Hanna or testing with the refractometer if the KH, Ca or Mg measurements are a bit off...

 

[Laith]

That seems to come up once in awhile and some use them interchangeably

I thought you could too. But they are very different:

For example, a density of 1.0225 gives you an SG of 1.026 at 27C. A density of 1.026 at 27C is actually an SG of 1.0296 or 39.3 ppt!

 

[ingchr1]

Well the SG does go up with the higher temp in the calculator I'm using (your example goes from 1.0251 to 1.0256 at the higher temp). Your example shows it doesn't go up to 1.0261 as the Hamza version shows.

I don't know why though... maybe a slightly different algorithm is used? But that doesn't make sense either.

In my case, my hydrometer measures Density, not SG (which I did not realize for a couple of months!). So I enter a temp of 27C and my density and get the SG/PSU results.

My example is a SG reading of 1.0256 at 80F.

Corrected to 77F, Hamza calculates 1.0261 while Reef App calculates 1.0251.

A 1.0251 SG at 80F in Hamza corrects to 1.0256.

Something doesn't seam right with how Reef App is presenting the results.

 

[KStatefan]

My example is a SG reading of 1.0256 at 80F.

Corrected to 77F, Hamza calculates 1.0261 while Reef App calculates 1.0251.

A 1.0251 SG at 80F in Hamza corrects to 1.0256.

Something doesn't seam right with how Reef App is presenting the results.

Using @Randy Holmes-Farley formula add 0.00019 for every degree F above the calibration temp, I adjust it to 1.02617

 

[ZipAdeeZoa]

I have a hannah salinity tester that I recalibrate every few months but had never had it drift and only because I’m paranoid I still have a sybon refractometer from when I started a few years ago that I use whenever I get the urge to double check but they always read the same thing.


I work at an LFS and I’ve heard this quite a bit about the hannah tester, when you get a solid one they’re awesome but I’d say about 15-20 percent seem to drift, sometimes a new battery fixes it but when your paying that much I feel like its reasonable to expect better than that.

they sybon is refractometer is a beast though, you can just feel the weight when you pick it up- its built super solid and I’ve never had it drift between calibrations.

 

[WVNed]

Swing arm hydrometer. A 10 year old one.
LOL

 

[Laith]

My example is a SG reading of 1.0256 at 80F.

Corrected to 77F, Hamza calculates 1.0261 while Reef App calculates 1.0251.

A 1.0251 SG at 80F in Hamza corrects to 1.0256.

Something doesn't seam right with how Reef App is presenting the results.

Using @Randy Holmes-Farley formula add 0.00019 for every degree F above the calibration temp, I adjust it to 1.02617

I agree, something is not right; there aren't two different formulas for calculating this.

I've emailed Kasper who I assume owns the reefapp site (at least his name and email is at the bottom of the page) to join the discussion or reply to me with his inputs...

 

[Kasper Tygesen]

Am I missing something or is this calculator correcting in the wrong direction? Here's a comparison to Hamza.

Also, would I first need to temperature correct the SG then convert that corrected value to get the PSU? The calculator shows PSU the same at both temperatures when entering a SG measurement.

Salinity Correction Calculator

Aquarium calculator; Correct a relative specific gravity (sg) measurement taken with a non-temperature-correcting unit.

www.hamzasreef.com

I agree, something is not right; there aren't two different formulas for calculating this.

I've emailed Kasper who I assume owns the reefapp site (at least his name and email is at the bottom of the page) to join the discussion or reply to me with his inputs...

Thank you for pointing out the error in the specific gravity calculation.
I have fix the sg to sg temperature conversion so it should be accurate now.

The description of the page was wrong. It doesn't support hydrometer correction even though the description said so. Previously I had a hydrometer correction calculator on the page along with the unit converter.
I just forgot to change the description when I removed the correction calculator.

I am sorry about the confusion.
The calculator should only be used to convert units not for temperature correction of hydrometers etc.