Apex Salinity Probe Calibration

[Jyetman]

I added and setup my conductivity probe back in July last year. After several calibrations got a reading of 34.0 which I thought was dead on compared to my Milwaukee MA877. Seven months later after probe drifted down to 33.7 I decided to recalibrated with new pinpoint 5300 solution. Now I get a new reading of 32.0 why? Tried calibrating twice same result.

 

[thegrun]

Did you follow the instructions, i.e. did you dry the probe for a few hours before calibration? Are you set up with a temperature probe attached to the PM2 module and the proper temperature offset?
If all of the above are correct I would contact Neptune Support for guidance.

 

[Jyetman]

Did you follow the instructions, i.e. did you dry the probe for a few hours before calibration? Are you set up with a temperature probe attached to the PM2 module and the proper temperature offset?
If all of the above are correct I would contact Neptune Support for guidance.

yep all of the above.

 

[Member No. 1]

From my personal experience, no matter how hard I tried, how careful I was, or how many times I tried, I could not get the probe to read right.
I have two refractometers, both calibrated with 35 ppm solution. The Apex was always different.
I don't take the readings from Apex for salinity as gospel, I always verify with the refractometers, but being anal, I would like it to read correctly. I'm using the readings to track trends, and not as a control input for ATO, or anything else.
I have the Apex set to conductivity so it reads mS/cm.
So to suppress my OCD twitch, I calibrated the probe to 53000 per the instructions, so on step two, instead of using the calibration solution, I just put the probe in it's normal location in my sump, and set it to the actual tank water level. Now it reads 53 mS/cm, daily swings are +/-.2 mS/cm and best part the twitch is gone!

 

[Waters40]

I believe you can also adjust the offset using the Classic dashboard. I just made sure mine matched my Milwaukee. I think it is used more for watching for salinity swings.

 

[Adrianm121]

I spent months battling with incorrect conductivity readings until I followed this procedure. Now I'm bang on the money

Try not using temp comp. If those steps give you equal results try the steps here. You an use the same calibration solution for a week or so. No need to open new bags just to do this each time.

1. Remove the Cond Probe from your PM2.
2. Remove the temp probe from your PM2. (If ANY)
3. Then go through the calibration again.
4. Aquacontroller Display : SETUP> COND SETUP
5. Set the Temp Comp to 0.0.
6. Click on COND CALIBRATE
7. Fail purposefully. It will reset to Defaults by clicking on SAVE, OK, SAVE, Etc.
8. Now Plug the Cond probe into your PM2
9. Now go to SETUP> COND SETUP> COND RANGE > SALINITY

Make sure the cond probe is plugged all the way in. Go to SETUP> COND SETUP> COND CALIBRATE.
1. It will say 'Dry Settling' This is the Dry Phase. Hold the cond probe out in the air for a minute and wait 1 minute. Then click OK
2. Now select your solution. use the up and down arrows to select 53000 then click OK
3. Then place the cond probe in the bag of solution. Keep it there for about 2 minutes then press OK.
4. It'll save and bring you back out to the menu. Click HOME and you're all done.
5. Keep the probe in the bag of solution and what does the cond probe read? It should read 34.9 or 35 ish.

If it read 34.9-35.0 in the solution the probe is capable of reading accurately and is operating correctly!

 

[CafeReef]

I spent months battling with incorrect conductivity readings until I followed this procedure. Now I'm bang on the money

Try not using temp comp. If those steps give you equal results try the steps here. You an use the same calibration solution for a week or so. No need to open new bags just to do this each time.

1. Remove the Cond Probe from your PM2.
2. Remove the temp probe from your PM2. (If ANY)
3. Then go through the calibration again.
4. Aquacontroller Display : SETUP> COND SETUP
5. Set the Temp Comp to 0.0.
6. Click on COND CALIBRATE
7. Fail purposefully. It will reset to Defaults by clicking on SAVE, OK, SAVE, Etc.
8. Now Plug the Cond probe into your PM2
9. Now go to SETUP> COND SETUP> COND RANGE > SALINITY

Make sure the cond probe is plugged all the way in. Go to SETUP> COND SETUP> COND CALIBRATE.
1. It will say 'Dry Settling' This is the Dry Phase. Hold the cond probe out in the air for a minute and wait 1 minute. Then click OK
2. Now select your solution. use the up and down arrows to select 53000 then click OK
3. Then place the cond probe in the bag of solution. Keep it there for about 2 minutes then press OK.
4. It'll save and bring you back out to the menu. Click HOME and you're all done.
5. Keep the probe in the bag of solution and what does the cond probe read? It should read 34.9 or 35 ish.

If it read 34.9-35.0 in the solution the probe is capable of reading accurately and is operating correctly!

just ordered a PM2 and probe yesterday, thank you for this.

Am I better off leaving my temp probe in my EB4 then? Or should I reroute it to the PM2?

 

[slief]

I spent months battling with incorrect conductivity readings until I followed this procedure. Now I'm bang on the money

Try not using temp comp. If those steps give you equal results try the steps here. You an use the same calibration solution for a week or so. No need to open new bags just to do this each time.

1. Remove the Cond Probe from your PM2.
2. Remove the temp probe from your PM2. (If ANY)
3. Then go through the calibration again.
4. Aquacontroller Display : SETUP> COND SETUP
5. Set the Temp Comp to 0.0.
6. Click on COND CALIBRATE
7. Fail purposefully. It will reset to Defaults by clicking on SAVE, OK, SAVE, Etc.
8. Now Plug the Cond probe into your PM2
9. Now go to SETUP> COND SETUP> COND RANGE > SALINITY

Make sure the cond probe is plugged all the way in. Go to SETUP> COND SETUP> COND CALIBRATE.
1. It will say 'Dry Settling' This is the Dry Phase. Hold the cond probe out in the air for a minute and wait 1 minute. Then click OK
2. Now select your solution. use the up and down arrows to select 53000 then click OK
3. Then place the cond probe in the bag of solution. Keep it there for about 2 minutes then press OK.
4. It'll save and bring you back out to the menu. Click HOME and you're all done.
5. Keep the probe in the bag of solution and what does the cond probe read? It should read 34.9 or 35 ish.

If it read 34.9-35.0 in the solution the probe is capable of reading accurately and is operating correctly!

Having calibrated Apex salinity probes many times and never having had an issue, there are a few things I would suggest. First is shaking the probe off in the drying phase. You don't want any residual water on the probe as that will contaminate the calibration solution.

Next, when you place the probe in the calibration solution, it's important to move the probe around in the solution a bit to get rid of any air in the probe tip as air bubbles in the tip will cause the probe calibration to be off. I twist the probe a couple times every minute or so for the first few minutes while allowing it to settle. I let the probe settle for several minutes. I don't feel 2 minutes is enough as the probe will still settle some after 2 minutes.

Lastly, it's best place a new probe in the tank water and leave it there for a few days before calibration.

I've had my Apex since they were first released and also had a PM2/conductivity probe since the PM2 was first released and never once had an issue with accuracy nor have I ever had an issue with calibration and I always follow the same steps. I have never had to reset the calibration points as mentioned above. I will also note that I do have a separate temp probe connected to my PM2.