Salinity/Conductivity Probe Calibration

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balloonpilot

Premium Member
What are the proper steps to calibrating the conductivty probe?

I've got the test solution.

What steps do i take and should I leave the Profilux reading SG or conduct (mS).
 
Great - And I saved the file this time since I lost the hard copy manual :)

But...

What is the prefered method for setting up the temperature compensation?

Do I select "measured value" and select the temp probe thats in my tank. Then place the sealed calibration fluid bottle in tank for few minutes and then take out and enter the tank temp as the calibration fluid temp?
 
So "measured value" basically sets it up to use the temp probe attached to profilux and as long as temp probe (tank water) is same as calibration fluid all is good... ?

Question - why couldnt I set the calibration up such that its using "measured", using attached temp probe but then put BOTH the temp probe and conductivity probe into calibration solution? That way, I would think, the calibration is performed to the actual temp of the calibration fluid.
 
You can do if your houdini and can fit two probes into a 14mm opening of the neck of the bottle :D

Joking aside, yes this is a better option of course if you can find a way to fit both probes into a container with enough calibration fluid covering the eletrodes adequately
 
I was thinking of just poring the calibration fluid into a cleaned out 'drinking glass' (after making sure its clean and dry).

That way if the calibration fluid changes time in the time it takes to do the actual calibration, it wont matter because the temp probe and cond probe would be in the same fluid.

So if I'm using 'Measured" and place my probes (temp and cal) into the fluid - Do I still need to enter any value for temp - Or will the system read the temp probe and adjust accordingly?

Also - I've got two bottles of solution - one is 50us (came w/ probe) and one is 53us (came w/ refractometer). Would it be better to use the 53us since thats spot on the 1.0264 SG reading I'm looking for?

Lastly - I see fluids are spec'd at their various readings (50 and 53) based on 25 deg celcius... So if the calibration fluid is not at 25, then the profilux will automatically adjust its reading during calibration?
 
Critical points -

1. The calibration and temp probe reading must be the same value as the fluid you will be monitoring (your tank water)

2. Use ONLY the GHL 50mS solution as this is what the software is set to.
 
"The calibration and temp probe reading must be the same value as the fluid you will be monitoring (your tank water)"

So its not a matter of getting the temp and cond probes at the same temp but its a matter of getting them and the fluid to be at tank temp ?

Do you still need to enter the tank temp, or does Profilux already know this because of the temp probe and being set to "measured"
 
in the software yes.

Follow the manual instruction calibrate it and see. it will make more sense when you do it
 
So in this manual where it says, "Next enter the temperature of the calibration fluid" - I should enter the tank temp because I'm going to set the fluid in the tank water so they are equal. Or does unit use the temp probe value for this as well?

Sorry so many questions, but I'm going to do this tonight (after your asleep) and I want to make sure I'm 100% of how and what to do before I start and get into it.
 
:crazy1: Im starting to get confused myself :hmm6:

Please wait until you are in front of it, I am online late as ever ;)
 
Okay I completed the calibration, I think :)

I took the bottle of calibration solution (50us) and placed bottle in plastic bag and placed that in tank for over an hour to make sure tank temp and solution were at same temp.

Set Profilux to 'seawater', temp sensor 1, and calibration to 50ms.

I was prompted for the TEMP of the calibration solution - Im assuming this in C not F...

So I finshed the cal and WOW... I must have done it wrong the fisrt time when I got my Profilux. I was under the assumption that my salinity was at 1.0264 but its NOT!

At your recommendation, I changed to reading Conductivity vice SG...

Which is a more accurate 'display' or 'reading'?

My probe is reading 57.2, when I toggle the Profilux between reading 'display' this equates to 37.52 (psu) and 1.0270 (density)... BUT... this doesnt match up to what Ive seen online...

For instance a converstion chart published by Randy (also on Reef Central):
57.1 should be 38 psu or 1.0286 density --- So why is my 57.2 showing a density of 1.0270 ???

Why would my readings be soo off from when I first calibrated? Could there have been that much of a difference between tank water and calibration solution the first time?
 
"I was prompted for the TEMP of the calibration solution - Im assuming this in C not F..."

And I'm assuming this is the actual temp - which since I've had the solution sitting in the tank is the same as the tank temp and NOT the value (25 c) printed on the bottle.
 
If asked the temp of the calibration then yes input it, the reading is in C.

In regards to SSG and mS, welcome to the mythical world of forums and advise!!!!

Simple answer there is NO industry standard for converting mS to SSG this is why I never use SSG only mS.

The average is 1.025 = 49-50mS

Make sure in the software you have entered your calibrated tank temp so if you calibrated and entered 28 degrees on the profilux make sure you enter that in the software.

Recalibrate tonight then once done put the probe back into the claibration and make sure the screen redig (not the software pc reading) reads within a few points of 50mS, if it does then you are calibrated.

Keep the reading in mS.
 
okay so my tank was sitting at 77.8 F (or 25.4 C) - So I set the Profilux to use measured temp and entered 25.4 as the temp of my calibrated solution (because I have the soltion sitting in the bottle in a plastic bag in the tank)... Correct ?

Then once calibrated and Profilux goes back into normation operations, I can take probe and place back into solution and should read close to 50mS... But what if the calibration solution temp is different than the tank temp at that point?
 
Yes but you still have to have the probe in "THAT" physical temp.

I think you are getting yourself quite stewed over this ;) Just follow the instructions and when you have done that, make sure the ProfiLux is reading within tolorence on the ProfiLux screen while the probe is still in the fluid in the tank.

There is nothing more to do other than that.
 
Okay one last different but related question...

Are the pH probes subject to the same temperature issue? And if so I should probably put them in the tank water during calibration too...
 
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