Worth recalibrating Apex salinity probe after short time?

AdamNC · Aug 6, 2019

Here's my salinity probe the past 6 days. I noticed it dropped dramatically on Fusion so I double checked it with my refractometer. It was a tad low at 1.024 sg. So I added a bit of salt to my ATO last night and today as you can see in the graph it's still low and even lower as the days go on. When I got home from work tonight I checked the bucket and it used about 2.5g of top off water. I just now checked with my refractometer after calibrating it and it's appears to be between 1.025 sg and 1.026 sg. So I dumped what was left in the top off bucket and refilled with fresh ro/di.

So my question is, should I re-calibrate the probe or give it a week and calibrate again or just leave it as is and watch for more trending?

#apexusers

rkpetersen · Aug 7, 2019

There's no drawback to recalibrating any time you feel the results might be inaccurate.
Aside from using up calibration solution packets.
Always use the manual recalibration process, rather than the automatic one. Give it lots of time to adjust.

AdamNC · Aug 7, 2019

Well even though I did it before, I flicked the probe lightly a few times at the top and I guess I finally dislodged some air bubbles. I guess I need to find a better spot, bubble free spot for it.

GainesvilleReef · Sep 28, 2019

The only time salinity probes should need to be recalibrated is when the controller probe combination has changed. It's usually bubbles or contamination. They should be given a soaking time before initial calibration.

Tastee · Sep 29, 2019

AdamNC said:
Well even though I did it before, I flicked the probe lightly a few times at the top and I guess I finally dislodged some air bubbles. I guess I need to find a better spot, bubble free spot for it.

I agree with your diagnosis - bubbles will quickly result in a false reading. You also need to be careful you don’t introduce any bubbles when you calibrate it as that will result in a false calibration.

I doubt it needs recalibration at this point. I did have to fiddle with my temperature compensation for several weeks to get that stable, and if you need to do this I recommend you recalibrate after you get that stable. I recalibrated mine at about month 4 after that and it has been stable for over 12 months since then.