Apex salinity probe calibration

[rkpetersen]

The Apex conductivity/salinity probe is not of the best design. With that acknowledged, here's how to get yours working consistently and well.

First, if you've done a calibration before and it seems to be messed up, simply recalibrating it is likely not going to do the trick. You need to reset the probe software in the controller and this is not well documented but I can vouch from personal experience that it definitely works and will save you much frustration. First, disconnect the probe from the jack on the Apex controller. Now do a manual calibration. Obviously this is a sham calibration since no probe is attached, so just go through the steps quickly and finish it. Then reboot your Apex (any of the several ways to do this is fine.)

Now reconnect your probe. You're ready to do a proper calibration. It needs to be a Manual calibration, not Automatic.

For the first phase, rinse the probe well in RODI water, shake it off gently and pat the end to remove excess moisture. You really don't have to make it bone dry, although you can blow a little pressurized gas through if you want. (I wouldn't let it dry overnight as some suggest, not necessary at all.) Start the manual calibration. The number should settle pretty fast. Go to phase two.

For the second phase, make sure you have the right solution, and make sure it is at your tank water temperature. Many people just tape the opened package to the inside of the sump. Or you can put the package in a beaker of water and make a water bath in your sump. Insert the probe, make sure it's submerged, let it sit with a swish every 30 seconds or so. Wait for number to settle for several minutes at least, until you're absolutely sure it's not moving anymore, and then complete the calibration.

If you have no defective hardware or offbeat software glitch, your probe should be working now.

 

[Vincent100]

@rkpetersen
Thanks for the info , I'm gonna try this and post back and let you know if it worked for me

 

[Kzguns]

The Apex conductivity/salinity probe is not of the best design. With that acknowledged, here's how to get yours working consistently and well.

First, if you've done a calibration before and it seems to be messed up, simply recalibrating it is likely not going to do the trick. You need to reset the probe software in the controller and this is not well documented but I can vouch from personal experience that it definitely works and will save you much frustration. First, disconnect the probe from the jack on the Apex controller. Now do a manual calibration. Obviously this is a sham calibration since no probe is attached, so just go through the steps quickly and finish it. Then reboot your Apex (any of the several ways to do this is fine.)

Now reconnect your probe. You're ready to do a proper calibration. It needs to be a Manual calibration, not Automatic.

For the first phase, rinse the probe well in RODI water, shake it off gently and pat the end to remove excess moisture. You really don't have to make it bone dry, although you can blow a little pressurized gas through if you want. (I wouldn't let it dry overnight as some suggest, not necessary at all.) Start the manual calibration. The number should settle pretty fast. Go to phase two.

For the second phase, make sure you have the right solution, and make sure it is at your tank water temperature. Many people just tape the opened package to the inside of the sump. Or you can put the package in a beaker of water and make a water bath in your sump. Insert the probe, make sure it's submerged, let it sit with a swish every 30 seconds or so. Wait for number to settle for several minutes at least, until you're absolutely sure it's not moving anymore, and then complete the calibration.

If you have no defective hardware or offbeat software glitch, your probe should be working now.

Awesome thanks

 

[Vincent100]

I tried 2times but each time it's reading in the 50s , I give up with it;Blackeye
Me and this probe will never get on , I'll go back to ignoring it lol

 

[rkpetersen]

Well nuts. Sorry it didn't help!

 

[Wiser]

The biggest issue I have seen is people not floating the solution so it is the same temp as the tank water. If you don’t match the temperature it will display an incorrect or crazy value.

Second if you have the probe in the solution and the system is displaying 35.0, you 100% know the probe is reading correctly.

Then if you stick it in the tank and the reading rockets then your salinity is probably high. Give it 24hrs to get a solid lvl though before you start fiddling.

BRS has a really good video with step by step guide.

 

[Ferrell]

For what its worth.
Ok so I had the same issue and spent hours on The apex forum trying this trying that and it all boiled down to this... leave it in your sump or whatever area you’re going to leave it for about a month, turn it off so you don’t get constant alarms and then try it again in a month. For whatever reason it worked.
I got tired of messing with it and one day turned it back on and viola, it read close to correct. Calibrated it to my confirmed 35 and done.

 

[Vincent100]

Well since messing with it last night it back to doing what it does best ... Bouncing all over the place
It's goes from 36.4ppt to 35.3ppt
My salt tests at 1.026 sg , 35ppt on my Milwaukee digital refractometer

Now do I take this jump from 35 to 36 as stable enough or should I still try fixing it

 

[SPR1968]

Well since messing with it last night it back to doing what it does best ... Bouncing all over the place
It's goes from 36.4ppt to 35.3ppt
My salt tests at 1.026 sg , 35ppt on my Milwaukee digital refractometer

Now do I take this jump from 35 to 36 as stable enough or should I still try fixing it

If you are happy that your Milwaukee is accurate enough (your happy with your system at its reading of 35ppt) then just use your tank water as the calibration fluid, and then it should all match. That’s what I did anyway and the Apex is around 0.5 higher than my trusty Red Sea Refractometer which is good enough.

Also try doing it with the manual calibration as well.

 

[Vincent100]

If you are happy that your Milwaukee is accurate enough (your happy with your system at its reading of 35ppt) then just use your tank water as the calibration fluid, and then it should all match. That’s what I did anyway and the Apex is around 0.5 higher than my trusty Red Sea Refractometer which is good enough.

Also try doing it with the manual calibration as well.

I'll have a go and post back and let you know
Thanks

 

[CindyKz]

Well since messing with it last night it back to doing what it does best ... Bouncing all over the place
It's goes from 36.4ppt to 35.3ppt
My salt tests at 1.026 sg , 35ppt on my Milwaukee digital refractometer

Now do I take this jump from 35 to 36 as stable enough or should I still try fixing it

If you have an ATO, the salinity will change as it kicks on and off. Especially if your probe is anywhere near where you are topping off.

Also, if I understand correctly (@Randy Holmes-Farley tell me if I"m wrong?) the salinity probe and your refractometer don't measure exactly the same thing. Salinity is salinity, specific gravity measures density of all substances (which for us is mostly but not all salt). So your probe and your refractometer aren't going to exactly match. You're monitoring trend anyway.

I would leave it alone for a couple of days and see what happens.

 

[siggy]

I've never been able to get mine working right ......don't even take any notice of it anymore

Mine is reading @44-45 , using the provided cal solution,I just don't
trust it until I can run multiple calibrations with 2 different solutions.
All my probes leaked there storage solutions and were dry when I installed , well 1 had a little fluid. Can they still be trusted?

 

[Randy Holmes-Farley Verified Community Expert]

Mine is reading @44-45 , using the provided cal solution,I just don't
trust it until I can run multiple calibrations with 2 different solutions.
All my probes leaked there storage solutions and were dry when I installed , well 1 had a little fluid. Can they still be trusted?

A conductivity probe should be stored dry, and at the very least, being dry doesn't hurt them. pH probes need to be in fluid all the time. Drying them is bad (with a few rare exceptions of unusual types that hobbyists are unlikely to use).

 

[siggy]

Ofcourse the PH probe was the worst offender

 

[Randy Holmes-Farley Verified Community Expert]

If you have an ATO, the salinity will change as it kicks on and off. Especially if your probe is anywhere near where you are topping off.

Also, if I understand correctly (@Randy Holmes-Farley tell me if I"m wrong?) the salinity probe and your refractometer don't measure exactly the same thing. Salinity is salinity, specific gravity measures density of all substances (which for us is mostly but not all salt). So your probe and your refractometer aren't going to exactly match. You're monitoring trend anyway.

I would leave it alone for a couple of days and see what happens.

While the things the different devices actually measure are different (refractometers: refractive index; conductivity probes: conductivity; hydrometer: density), the values should match within the precision of hobby devices since they are presumably calibrated to read seawater correctly, and the deviations from seawater are generally not sufficient to cause clear differences.

 

[griff500]

Mine has only maintained an accurate reading when I have calibrated using the tank water rather than the calibration fluid. Weird.

 

[CindyKz]

When I had trouble with my pH probe the problem turned out to be stray current from a float switch. When I removed the float switch the problem went away. Apex had me check for that by dipping out a cup of tank water, putting the probe in the cup and checking the reading. Have you tried that?

 

[tmcca]

I tried 4 times and finally got mine working...

This is what I did.. Took probe out of tank and dried it and should read zero. If it don't read zero either not dried or TC factor maybe off mine was mine read 0.4 and my TC was 2.2 and put it at 1.9 now reads Zero. I set my tank at 77 degrees and verified at 77 with my scientific thermometer and let the solution sit in my sump for 30 minutes and verified temp at 77 degrees.

Went to manual calibration let it settle should be in between 60-90; mine was 80

Next put it in 53~ solution wait for it to settle at least 5 min; mine settled at 1000

In solution read 34.9; in my tank reads at 34.9 ppt.

My milwaukee though reads 35ppt now .1 ppt no big deal. Some people though heard calibrate it with tank..