Should i trust icp salinity?

[WhatCouldGoWrong71]

lol. Because it measures specific gravity not ppt :-)

Specific gravity varies with temperature.

PPT doesn’t?

 

[Randy Holmes-Farley Verified Community Expert]

PPT doesn’t?

Salinity in ppt cannot ever change with temp. It is mass salt per mass water.

Specific gravity does really change much either, depending on how it is defined.

But a glass hydrometer reading changes a lot with temp and needs correction.

Conductivity meters and most refractometers automatically correct for temp changes in conductivity and refractive index .

 

[WhatCouldGoWrong71]

Salinity in ppt cannot ever change with temp. It is mass salt per mass water.

Specific gravity does really change much either, depending on how it is defined.

But a glass hydrometer reading changes a lot with temp and needs correction.

Conductivity meters and most refractometers automatically correct for temp changes in conductivity and refractive index .

@Randy Holmes-Farley how do you personally test for salinty? If I can get my mixing station dialed in and my tank and mixing station are in sync, then, I don’t test as much and my anxiety around salinity swings are much lower, lol.

 

[Miami Reef]

For whatever reason, he likes conductivity probes.

I never had luck with the Apex one…the results kept shifting and I needed to shake the probe. It didn’t hold calibration, either.

Maybe he uses more bougie ones…or maybe I just had a faulty probe.

Maybe I should try again.

 

[Randy Holmes-Farley Verified Community Expert]

@Randy Holmes-Farley how do you personally test for salinty? If I can get my mixing station dialed in and my tank and mixing station are in sync, then, I don’t test as much and my anxiety around salinity swings are much lower, lol.

When my conductivity meters I’ve been using for the past 30 years died, I recently bought another old school conductivity meter on eBay.

 

[Randy Holmes-Farley Verified Community Expert]

It shows 1.027. I always test 1.025 using my milwaukee ma877

Some icp companies, such as Oceamo, tell you how they measure things such as salinity (conductivity) and alkalinity (pH titration). I would trust the Oceamo values. I do not know how triton does it.

 

[Randy Holmes-Farley Verified Community Expert]

For whatever reason, he likes conductivity probes.

I never had luck with the Apex one…the results kept shifting and I needed to shake the probe. It didn’t hold calibration, either.

Maybe he uses more bougie ones…or maybe I just had a faulty probe.

Maybe I should try again.

I don’t leave the probes in tank water. None that I previously had were able to be calibrated, just checked.

This VWR meter is easily calibrated and I’ve been doing it frequently since it takes less than a minute.

 

[Notsolostfish]

For whatever reason, he likes conductivity probes.

I never had luck with the Apex one…the results kept shifting and I needed to shake the probe. It didn’t hold calibration, either.

Maybe he uses more bougie ones…or maybe I just had a faulty probe.

Maybe I should try again.

Just want to update the thread. I checked the older icp tests from triton i did last year. And it also showed 1.028. That’s completely wrong. Because on those times, i had the hydrometer bu tropic marin, and they read 1.025 like my milwaukee, making the icp test completely wrong in my opinion

 

[Notsolostfish]

Some icp companies, such as Oceamo, tell you how they measure things such as salinity (conductivity) and alkalinity (pH titration). I would trust the Oceamo values. I do not know how triton does it.

Thats what it says how they do it

 

[gbroadbridge]

Thats what it says how they do it

What it says is that they calculate the salinity based upon the elemental composition of the sample, rather than measuring it.

 

[Notsolostfish]

Thats what it says how they do it

What is says is that they calculate the salinity based upon the elemental composition of the sample, rather than measuring it.

So is that accurate or not accurate?

 

[gbroadbridge]

So is that accurate or not accurate?

Randy's the best person to comment, but it is going to depend upon what they consider to be a 'normal' composition of water and how they calculate based on that.

My experience is that compared to a reference which is made using Randy's DIY conductivity recipe, *my* tank water always reads around 37psu according to the local Trident lab ICP.

My process is to align my tank with my standard and ignore Triton as I only ICP once a year.

If you're doing an ICP every couple of weeks you may as well use their number as it is not far enough different to make any real difference.

Consistency is more important than the actual number, within reasonable limits.