Salinity probe calibration question

[BAMatter]

Having a difficult time getting my probe calibrated for my Hydros X10, and had a question that seems to be overlooked in my back and forth with Coralvue. They seem to think it’s a calibration fluid issue. My tank is 35ppt according to my Milwaukee digital refractometer, and was 35.5ppt on my last ICP test.

Here’s the question- I have 28ppt and 35ppt calibration fluids. Does a refractometer accurately read these? My Milwaukee is reading them both at 28ppt and 35ppt respectively, so if that’s the case, does this mean that the fluids are fine? Just didn’t know if the fluids read correctly on a refractometer or if they could actually be bad…

Sorry if that’s a bit confusing… Thanks.

 

[TX_REEF]

Having a difficult time getting my probe calibrated for my Hydros X10, and had a question that seems to be overlooked in my back and forth with Coralvue. They seem to think it’s a calibration fluid issue. My tank is 35ppt according to my Milwaukee digital refractometer, and was 35.5ppt on my last ICP test.

Here’s the question- I have 28ppt and 35ppt calibration fluids. Does a refractometer accurately read these? My Milwaukee is reading them both at 28ppt and 35ppt respectively, so if that’s the case, does this mean that the fluids are fine? Just didn’t know if the fluids read correctly on a refractometer or if they could actually be bad…

Sorry if that’s a bit confusing… Thanks.

ICP tests can't always be trusted for salinity from what I read. Refractometers should be your go-to source of truth when properly calibrated, check out this article by @Randy Holmes-Farley if you have doubts on the quality of your calibration solutions: https://reefkeeping.com/issues/2004-06/rhf/index.php

 

[KStatefan]

Here’s the question- I have 28ppt and 35ppt calibration fluids. Does a refractometer accurately read these? My Milwaukee is reading them both at 28ppt and 35ppt respectively, so if that’s the case, does this mean that the fluids are fine? Just didn’t know if the fluids read correctly on a refractometer or if they could actually be bad…

Sorry if that’s a bit confusing… Thanks.

That would depend on what the calibration solution was made to. Randy's DIY is only good for one measuring device. A commercial purchased one might be. Does it state what it reads? ie
1.0264 Specific Gravity
1.3394 Refractive Index
53 mS/cm at 25 deg C

 

[BAMatter]

That would depend on what the calibration solution was made to. Randy's DIY is only good for one measuring device. A commercial purchased one might be. Does it state what it reads? ie
1.0264 Specific Gravity
1.3394 Refractive Index
53 mS/cm at 25 deg C

This is the solution.

35ppt Salinity Calibration Fluid (100mL)

HYDROS Salinity Reference Solution is highly recommended for calibration of refractometers, hydrometers, and salinity/conductivity equipment. It's one of the two necessary components for calibrating HYDROS Salinity Probes.

www.coralvue.com

Also have it in 28ppt

 

[KStatefan]

This is the solution.

35ppt Salinity Calibration Fluid (100mL)

HYDROS Salinity Reference Solution is highly recommended for calibration of refractometers, hydrometers, and salinity/conductivity equipment. It's one of the two necessary components for calibrating HYDROS Salinity Probes.

www.coralvue.com

Also have it in 28ppt

"For precise calibration of refractometers, hydrometers, and salinity/conductivity equipment,"

 

[BAMatter]

"For precise calibration of refractometers, hydrometers, and salinity/conductivity equipment,"

That’s what I saw as well. So if all else is equal, and a digital refractometer confirms both 35ppt and 28ppt, and the probe isn’t holding calibration, then it’s likely a probe issue I’m assuming? I’m being told it’s most likely the calibration fluid being inaccurate, but I’m not inclined to think that way at this point.

 

[Robert Minett]

Simply put, as the bottle reads "1 time use". If you put the probe in the bottle to calibrate it, then NO you can not reuse it. It is now contaminated from having it in your tank prior to calibration. Buy new fluid and put a small amount in a small beaker before calibrating.

 

[Randy Holmes-Farley Verified Community Expert]

Simply put, as the bottle reads "1 time use". If you put the probe in the bottle to calibrate it, then NO you can not reuse it. It is now contaminated from having it in your tank prior to calibration. Buy new fluid and put a small amount in a small beaker before calibrating.

Well, I reuse it all the time. I just rinse the probe with RO//DI after each use, and if it is still wet when I want to use it again, I shake the probe dry.

FWIW, I use a large amount of calibration fluid in a bottle and drop the probe into it for a each before each use. Tiny bits of either RO/DI or tank water are not going to appreciably change it.