Apex Salinity probe vs. Hanna not adding up

[MarkBenoit]

Hi all, Newbie here. I bought a Neptune Apex and installed it in my Reefer 250. Up until now (8 days in) I’ve been using a Hanna Salinity tester and have been getting perfect readings of 1.025 - 1.026. The device has been calibrated twice for certainty. The Apex probe, also calibrated, is showing 39.2 ppm (1.0296). I’m really not sure what reading is accurate and now don’t know what to trust. I have put the Apex salt probe in a 35ppm test solution (from the Hanna kit) along with the temp probe and it reads 31.6

Any suggestion on how to get all this aligned would be greatly appreciated…

 

[T-J]

Apex salinity probe sucks. If you want to even have a chance of it reading correctly, get the aftermarket S.P.S. kit for it. Otherwise, just stick to the Hannah.
Even if you do get them to match at some point, it's better to choose one to follow, which will be more stable.

 

[PeterC99]

When you have 2 divergent readings from 2 different testers, very important to get a 3rd different opinion. Go to local fish store with a sample of your saltwater and that will tell you which tester is more accurate.

 

[Gtinnel]

Near the bottom of this article there are directions to make a testing standard for conductivity testers. It's simple and cheap to make so you can test both of them against a known solution.
I use this article to make the refractometer solution and it works perfectly, I haven't made the conductivity solution but I'm sure it's just as good since Randy wrote the article.

http://www.reefkeeping.com/issues/2004-06/rhf/

 

[MarkBenoit]

Thanks for the replies everyone! I will try the testing standard recipe and go to my local shop for a comparison. Will also order the SPS kit…

 

[MarkBenoit]

Alright, with some support from the folks at Neptune I was able to diagnose and correct the problem. The Salinity probe is now calibrated and working they way it was intended to. Thanks to all for the suggestions and support!!

 

[ssdawood]

Care to post. Will help other people in calibrating theirs. Everyone says Salinity probe is not good. But you can't buy one.
Of course some people have it calibrated right and using it.

Thank you. Help will be appreciated.

 

[MarkBenoit]

Care to post. Will help other people in calibrating theirs. Everyone says Salinity probe is not good. But you can't buy one.
Of course some people have it calibrated right and using it.

Thank you. Help will be appreciated.

Great comment. Didn't think of it but will go now to post solution...

 

[MarkBenoit]

Hi all, I received a good suggestion that I should post the fix that finally worked to get my Apex Salinity probe calibrated and working properly so here it is:

I followed the manual calibration, not the automatic calibration, instructions to the letter (copied below) as provided by Neptune. The difference this time was how well I cleaned and dried the probe prior to calibration. This included a good but gentle rinse in RO/DI water for about 30 seconds and making sure that the probe was wiped dry and had no lingering water inside the tube. A few gentle taps on a dry cloth helped to dislodge any remaining water. I then waited several minutes before attempting to calibrate, maybe 5-6.

From there I followed the prescribed steps and it all worked as described. Nothing magic here unfortunately but thankful that it now works and can be verified against other calibrations for accuracy notably my Hanna calibration tool and my local shop...

I hope this helps. Happy trails...

MANUAL CALIBRATION (credit to Neptune Apex Support team)

Step 1:
Start by logging into your APEX Dashboard and clicking on the Three Gears Icon and then the INPUTS Icon

Step 2:
Select the SALT(BASE_COND) Option.

Step 3:
Ensure you have the Conductivity Probe securely plugged into the APEX.

Step 4:
Click on the ADVANCED Tab option.

Step 5:
Scroll down and click on the MANUAL PROBE CALIBRATION option.

Step 6:
Follow the steps it prompts you to do. Press the Calibrate button.

Air dry the Conductivity Probe. (This can take 1 minute or less to dry) *note:Some customers have used canned air

Step 7:
Next Select Ok once the probe has settled (the values not changing after 15-30 seconds)

*Note the typical settling number range is 60-90 when calibrating Dry

Step 8:
Select the Calibration Solution you are about to use.

*Note the Apex base unit can ONLY calibrate using 53,000, a PM2 module can offer other ranges

Step 9:
Dip the Conductivity Probe into that calibration solution. Ensure to gently swish the probe, so as to avoid micro bubbles on the surface of the probe.
This settling number may not completely stop. But, generally when it's settling down go ahead and click next. (once the values hold from changing for 15-30 seconds)

*Note the typical settling number range is 200-900 when calibrating in the 53,000 Solution

Step 10:
Now you will get this message that you have successfully calibrated the probe

Step 11:
Once the calibration is complete your Salt reading on the APEX Dashboard should read around 34.7~35.3 inside of that packet of calibrating solution. In dry air, the probe will read 0. In the solution it will read 34.7~35.3. If it does then the probe is calibrated successfully. You are now complete!

Note: You can save the calibration fluid for a couple days if you seal up the solution packs when not in use.

Please send us the results of:
1) Settling number from step #7 - Dry
2) Settling number from step #9 - In the Cal solution
3) Settling number from step #11 - In the Cal solution
4) Settling number in the tank

 

[KStatefan]

Near the bottom of this article there are directions to make a testing standard for conductivity testers. It's simple and cheap to make so you can test both of them against a known solution.
I use this article to make the refractometer solution and it works perfectly, I haven't made the conductivity solution but I'm sure it's just as good since Randy wrote the article.

http://www.reefkeeping.com/issues/2004-06/rhf/

I use Randy's recepie scaled up to fit in a 1 liter water bottle.

 

[Gtinnel]

I use Randy's recepie scaled up to fit in a 1 liter water bottle.

I didn't mention it but I scaled it up also so that small inconsistencies in my cheap scales doesn't effect the resulting salinity. I then threw most of it away and just kept a small bottle of it, since it costs almost nothing to make. It amazes me that there are people that buy the bottles of solution when it is so easy and cheap to make.