Xplain, PPT to SRG no way to convert apples to apples ?

[Val Shebeko]

Ocean water? No reason to assume it is any particular salinity.

Shows What I know.

 

[Myka]

Salinity drives me freaking bonkers too. You can't even buy 2 seawater calibration fluids that agree with each other! Sybon and TLF are 2 ppt apart!

See how close it comes to 1.0350.

You're confusing salinity and ppt numbers. Don't do that when you're checking or you'll really drive yourself nuts! Haha!

 

[Val Shebeko]

Salinity drives me freaking bonkers too. You can't even buy 2 seawater calibration fluids that agree with each other! Sybon and TLF are 2 ppt apart!



You're confusing salinity and ppt numbers. Don't do that when you're checking or you'll really drive yourself nuts! Haha!

Tell me more please. Because I am confused.

 

[Hooloovoo]

Tell me more please. Because I am confused.

I think he Myka meant that, if you are measuring in ppt, you are usually shooting for a value around 34-35; whereas if you are measuring s.g., you are usually shooting for something like 1.025-1.026. 1.035 would be a crazy high value for s.g.

 

[Val Shebeko]

I think he Myka meant that, if you are measuring in ppt, you are usually shooting for a value around 34-35; whereas if you are measuring s.g., you are usually shooting for something like 1.025-1.026. 1.035 would be a crazy high value for s.g.

Correct. That is exactly what is happening. But why ?

 

[Myka]

Correct. That is exactly what is happening. But why ?

"But why", what??

 

[Val Shebeko]

"But why", what??

Why the disparity.?

When I convert temp. from degresss C to F I get equivilents, here going from Salinity expressed in Ppt to Sg not so much.

 

[Randy Holmes-Farley]

Why the disparity.?

When I convert temp. from degresss C to F I get equivilents, here going from Salinity expressed in Ppt to Sg not so much.

I don't know what you are finding confusing. There is an EXACT relationship (within rounding errors and experimental measurement capabilities and some different technical definitions for things like specific gravity) between salinity of seawater and the specific gravity. It can be looked up in any number of tables, including table 1 in one of my articles:

Reef Aquarium Salinity: Homemade Calibration Standards by Randy Holmes-Farley - Reefkeeping.com
http://reefkeeping.com/issues/2004-06/rhf/index.htm

 

[Val Shebeko]

I don't know what you are finding confusing. There is an EXACT relationship (within rounding errors and experimental measurement capabilities and some different technical definitions for things like specific gravity) between salinity of seawater and the specific gravity. It can be looked up in any number of tables, including table 1 in one of my articles:

Reef Aquarium Salinity: Homemade Calibration Standards by Randy Holmes-Farley - Reefkeeping.com
http://reefkeeping.com/issues/2004-06/rhf/index.htm

The Apex is reporting near 44 of salinity and my refractometer purchased for 20 dollars and carrefully maintained and calibrated are wildly different. So... I thought I would ask.

Apex has no particular answer. Answers seems be you should not expect it. If I misunderstood Apex, I apolgize in advance and promise to drink a cup of tank water as atonement.

So.

I have ordered for some 200 dollars a new refractometer made by True Sine and calibration fluid for it made by True Sine.
Because I am given to understand my regular refracrometer only measures the brine content of the water but this one actually measures correctly. Not really sure why that is but....

I have ordered calibration fluid from Apex for the Apex probe and have discovered that someplace in advanced setting there is a place to let the probe know what the water temp. is. Why the probe is not smart enough to ask the temp. probe is beyound me. Seems a 1200 dollar controller would be able to do that. But ok.

When everything is here and recalibrated I will post the results of my enquiry.

I am posting two screen shots of my experience thus far.

 

[Val Shebeko]

I don't know what you are finding confusing. There is an EXACT relationship (within rounding errors and experimental measurement capabilities and some different technical definitions for things like specific gravity) between salinity of seawater and the specific gravity. It can be looked up in any number of tables, including table 1 in one of my articles:

Reef Aquarium Salinity: Homemade Calibration Standards by Randy Holmes-Farley - Reefkeeping.com
http://reefkeeping.com/issues/2004-06/rhf/index.htm

What the Apex salinity probe is reporting and what the refractometer is showing in my case is very very different. The probe is report near 44 and the refractometer is at 1.025.

APEX has no particular answer. Answers seems be you should not expect it. If I misunderstood Apex, I apolgize in advance and promise to drink a cup of tank water as atonement.

So.

I have ordered for some 200 dollars a new refractometer made by True Sine and calibration fluid for it made by True Sine.
Because I am given to understand my regular refracrometer only measures the brine content of the water but this one actually measures correctly. Not really sure why that is but....

I have ordered calibration fluid from Apex for the Apex probe and have discovered that someplace in advanced setting there is a place to let the probe know what the water temp. is. Why the probe is not smart enough to ask the temp. probe is beyound me. Seems a 1200 dollar controller would be able to do that. But ok.

When everything is here and recalibrated I will post the results of my enquiry.

I am posting two screen shots of my experience thus far.

 

[Val Shebeko]

Sorry for what might be a double post. My iPad this morning has decided to assert its independence.

 

[Breadman03]

I had trouble figuring out why my Apex probe was so far off of my refractometer and hydrometer. I switched the conductivity range to high and the numbers made sense. I don't think there's any way to change that in Fusion unless you're running the 2016 Apex, which it appears you have.

 

[Val Shebeko]

I had trouble figuring out why my Apex probe was so far off of my refractometer and hydrometer. I switched the conductivity range to high and the numbers made sense. I don't think there's any way to change that in Fusion unless you're running the 2016 Apex, which it appears you have.

Where do I find the setting on APEX ?

 

[Randy Holmes-Farley]

What the Apex salinity probe is reporting and what the refractometer is showing in my case is very very different. The probe is report near 44 and the refractometer is at 1.025.
.

Are you certain the Apex is giving ppt and not mS/cm as the units?

 

[Val Shebeko]

Are you certain the Apex is giving ppt and not mS/cm as the units?

No, no I am not. Where do I find that setting ?

 

[Breadman03]

Where do I find the setting on APEX ?

On the Classic, one would find it under module setup. I'm not sure where you would find it with the 2016, but would look around where you calibrate from.

 

[Randy Holmes-Farley]

I've never used an Apex so can't comment on its details.

When you calibrated, what value did the standard show and what standard was it?

 

[Hooloovoo]

I have the Apex 2016, and as far as I can see, it only gives the salinity reading in ppt. Sounds to me like Val Shebeko is having calibration issues, or he has a bad probe. Based on the number of threads I have seen from people having problems calibrating their Apex conductivity probes, I would say that it is not a simple matter. I had trouble with mine initially too, but I now have it reading reasonably consistent with my refractometer. It took me three attempts to get it calibrated to that point though.

FYI, my refractometer is one of those designed for saltwater rather than marine. I calibrate it to a 35 ppt refractive calibration solution before each use though, so it should be sufficiently accurate within my target range. The instructions that it came with actually said to calibrate to distilled water, and the guys at World Wide Corals where I bought it told me they just calibrate with RO/DI. After reading RHF's article about refractometers though, I did some testing and confirmed that calibrating it that way does not produce accurate results for this refractometer if you are using it for marine applications.

Note: I initially made the mistake of trying to recalibrate my conductivity probe using the same standard I use to calibrate my refractometer. This produced results that were way off. The apex calibration solution is for calibrating conductivity probes, and the calibration solution for the refractometer is for devices that measure refractive index. If these solutions were simply known concentrations of seawater, I would expect that they would be interchangeable, but that apparently is not the case.

 

[Hooloovoo]

On the Classic, one would find it under module setup. I'm not sure where you would find it with the 2016, but would look around where you calibrate from.

I don't think the 2016 has the option to display in anything other than ppt. If it does, they have hidden it very well.

 

[Terence]

The 2016 Apex is designed to only show conductivity as salinity (that conductivity range) in ppt.