Conductivity Probe or Refractometer

[ReefAddict]

So my Apex conductivity probe reads 2-3 points higher than my refractometer.  Now I know they are technically measuring different things, but which would you recommend following.  I'm at 1.026 or 35 on my refractometer, which I have always used on all of my tanks.  I setup my apex fusion a few weeks ago and it measures in the high 37's.  Should I adjust to the Apex or stick with the refractometer?   Both were calibrated as per included instructions. 

 

 

[dpassar12]

How long has the APEX probe been in the tank? I use both and both are very accurate. Check for air bubbles in the probe. I would go with the meter over the probe, less margin for error on the calibration and use.  

Try mixing a gallon of water that you know is correct and test both... make sure you put the temp probe in the test.. 

Edited March 3, 2017 by dpassar12

[AlanM]

I don't know how complicated the conductivity measurement is, if it can be thrown off by other ions that wouldn't show up in the refractometer.  I'd go with dpassar12 and trust the calibrated refractometer initially over the probe.  You sure your refractometer is calibrated correctly?

[mr.x-ray]

Sounds like your refractormeter is calibrated and probe is not. Using a known solution to adjust your meter (calibration) and following directions on setup from apex are two different things. You can calibrate one as the master and adjust the other to that or use the same solutions on both. And like above, the probes are subject to added issues. Use the probe to keep an eye on the tank but use your refractormeter to check every so often.

[ReefAddict]

Here's what Neptune Systems had to say:

 

To clarify, the conductivity probe functions by measuring the displacement of NaCl ions in the water.  The conductivity probe is not a refractometer.  It's not going to read like your refractometer.  This is common. It's a conductive sensing probe.  Your refractometer is designed to detect specific gravity/density of all the salts in your water like KCl, MgCl, not just NaCl, but the conductivity probe will give you a closer look at the true salinity (ppt) reading in your aquarium.   

 

I got this response in less than two hours after letting them look at my system.  Pretty awesome customer service.  So I guess I will test the probe in the calibration solution to make sure it is still calibrated correctly and then re-evaluate.

Edited March 3, 2017 by ReefAddict

[Origami]

Make sure that you calibrate the refractometer with a solution meant for refractometer and likewise for the conductivity probe. Each device measures something different and will require different solutions (since the solutions are likely just saline in different concentrations) .

 

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[zygote2k]

conductivity probes are in my opinion a PITA because they constantly need to be cleaned and calibrated. A good refractometer is best.

[Origami]

conductivity probes are in my opinion a PITA because they constantly need to be cleaned and calibrated. A good refractometer is best.

+1

 

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