Help! Salinity isn't adding up

[ArnoldosAquariums]

This whole... struggle... has made me feel like a newbie again, lol.

Long story short- one of my tanks recently got an ICP test done (I do it every 6 months via ATI). My salinity tested (with a Milwaukee tester @ 1.022-34 SG. It was a low, as I usually aim for 1.025. However, ICP came back with VERY low salinity.. he said PPT was under 30.

I took a salt sample and my tester to my LFS. She said even their water my tester came at 1.022 but my water on their tester (same type) was .024.
Despite calibrating it multiple times (I always calibrate to 0 with distilled) it always read .002 lower. Ok.. weird... so If .024 is what I'm at, why did ATI say salinity is low?

They said they don't go by SG but rather PPT.

If I increase my PPT (30) to go up to 35.. my SG will go through the roof. Either my brain is fried or I'm not understanding the correlation between the two anymore. I always thought 35ppt = 1.026 S.G.

Thanks in advance!

 

[TangerineSpeedo]

If your salinity was 1.022 as tested when you sent your sample. It was under 30 ppt.
Use this calculator.

Salinity Conversion Calculator

Aquarium calculator; Convert salinity between relative specific gravity (sg), parts-per-thousand (ppt), and units of conductivity (mS/cm).

www.hamzasreef.com

 

[Naekuh]

Well common sense says if your tester is giving bad results compared to 2 different sources, then your tester must be bad.

Get a refractometer, and if the refractometer is showing the same result, your milwaukee maybe broken.

 

[ArnoldosAquariums]

If your salinity was 1.022 as tested when you sent your sample. It was under 30 ppt.
Use this calculator.

Salinity Conversion Calculator

Aquarium calculator; Convert salinity between relative specific gravity (sg), parts-per-thousand (ppt), and units of conductivity (mS/cm).

www.hamzasreef.com

Except 1.022 on my Milwaukee = 1.024 as tested.

So how does 1.024 = >30ppt?

 

[Naekuh]

Except 1.022 on my Milwaukee = 1.024 as tested.

So how does 1.024 = >30ppt?

It doesn't which is why im saying i think your tester is broken, since all calibration attempts aren't working.

Get another tester to cross test.
If the secondary tester is the same as milwakee, then it comes down to your testing methodolgy.

If the second tester backs up the other tests results, then you have a broken milwaukee.

 

[TokenReefer]

She said even their water my tester came at 1.022 but my water on their tester (same type) was .024

Can you clarify what you mean here?

 

[ArnoldosAquariums]

Can you clarify what you mean here?

My tester is .002 off

 

[TokenReefer]

My tester is .002 off

Oh, glad you figured it out. Between Icp, lfs and your Milwaukee... Something is

 

[gbroadbridge]

My tester is .002 off

That is within the stated uncertainty of the device.

There is nothing wrong with it.

 

[Justfebreezeit]

Get the tropic marin hydrometer and be done with it.

 

[Hats_]

This whole... struggle... has made me feel like a newbie again, lol.

Long story short- one of my tanks recently got an ICP test done (I do it every 6 months via ATI). My salinity tested (with a Milwaukee tester @ 1.022-34 SG. It was a low, as I usually aim for 1.025. However, ICP came back with VERY low salinity.. he said PPT was under 30.

I took a salt sample and my tester to my LFS. She said even their water my tester came at 1.022 but my water on their tester (same type) was .024.
Despite calibrating it multiple times (I always calibrate to 0 with distilled) it always read .002 lower. Ok.. weird... so If .024 is what I'm at, why did ATI say salinity is low?

They said they don't go by SG but rather PPT.

If I increase my PPT (30) to go up to 35.. my SG will go through the roof. Either my brain is fried or I'm not understanding the correlation between the two anymore. I always thought 35ppt = 1.026 S.G.

Thanks in advance!

ICP get salinity wrong often, since they usualy measure it by calculation instead of individual measurement. i cant speak for how ATI measures it but id trust a properly calibrated refractometer over any ICP test

 

[Randy Holmes-Farley Verified Community Expert]

As noted, the Milwaukee has a wide stated uncertainty range.

I think all of the values are consistent with the expected variability/error range around a sg of 1.023 which is ~ 30.5 ppt.

 

[ArnoldosAquariums]

Get the tropic marin hydrometer and be done with it.

That’s exactly what I just did, and I wish I had done this sooner.

 

[Randy Holmes-Farley Verified Community Expert]

I would just advise that folks using glass hydrometers of any sort to do two things:

1. Test them at least once to be sure they are sufficiently accurate.

2. Be sure to be aware of how temp impacts the reported values.

 

[TangerineSpeedo]

I would just advise that folks using glass hydrometers of any sort to do two things:

1. Test them at least once to be sure they are sufficiently accurate.

2. Be sure to be aware of how temp impacts the reported values.

Yes. Temperature affects accuracy. There is no ATC with these.

 

[Malum Argenteum]

(I always calibrate to 0 with distilled)

Calibrate with a standard that is within the expected range you'll be testing. A meter can read correctly at zero and incorrectly otherwise.

 

[JustAnotherNanoTank]

Get a good ol refractometer to back up the digital one.

If your digital one is always a little off, get the tank to where you want it on the refractometer then what ever number the digital gives you, accept that as correct.

Always hit the refractometer every once in a while to check on the digital guy.

You’ll be good to go.