Salinity probe replacement

[lavoisier]

I have an old salinity probe (6 or 7 years) that has served me faithfully. I just attempted to calibrate it (I do it monthly) and it reads over 39 in the 53000 solution and it is out of the "acceptable range" on my apex. Does this mean the probe has finally failed?

 

[Randy Holmes-Farley Verified Community Expert]

39 ppt?

 

[lavoisier]

Yes

 

[Randy Holmes-Farley Verified Community Expert]

Reading high does not sound like a faulty probe. In my experience, they fail to read at all from a broken electrical connection, or they read low due to excessive fouling.

Maybe the solution is off?

 

[lavoisier]

A puzzle. As chance would have it, I used calibration fluid from two separate batches. But you give me hope. I'll thoroughly dry probe overnight, order calibration fluid from a different source, and try again.

 

[lavoisier]

I received a new batch of calibration fluid and dried the probe overnight. The probe read 36.3 in the 53000 solution! Time for a new probe?

 

[Randy Holmes-Farley Verified Community Expert]

I received a new batch of calibration fluid and dried the probe overnight. The probe read 36.3 in the 53000 solution! Time for a new probe?

Presumably that is 36.3 ppt? If so, that isn't far off of 35 ppt. If you can calibrate it to read 35, I'd do that. If it cannot be calibrated, just subtract 1.3 ppt from readings near 35 ppt.

 

[boacvh]

I had similar issue when calibrating mine recently. Read 43ppt no matter what I did. This is how I fixed mine. Credit to @rkpetersen in this thread

Apex salinity probe calibration

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...

www.reef2reef.com

-Remove probe from apex
-Make a fake calibration (manual, so just go through the steps quickly and finish it)
-Reboot your apex (I just unplugged mine)
-Reconnect probe
-and do MANUAL calibration with the packet (make sure no micro bubbles on the probe, etc)
That fixed it for me. maybe it helps you.

 

[lavoisier]

Thank you for your replies. I like both your ideas as they save me $125. I'll try boacvh suggestion and if it continues to read high, I'll follow Randy's.

 

[rkpetersen]

Thank you for your replies. I like both your ideas as they save me $125. I'll try boacvh suggestion and if it continues to read high, I'll follow Randy's.

Which Randy?

 

[AcanthurusRex]

After the last one failed I removed it. Saved money and time. I would never trust it for automation so I don't see any reason to replace it.

 

[lavoisier]

You make a good point. I also do not use it for any automated adjustments. However, I have a large tank, and live in the midwest, so humidity is always in flux, often from one day to the next. I do not always have the discipline to manually check my salinity a couple of times a day so the probe can alert me to possible issues. If it does, then I'll manual check to confirm or ignore the reading.

Which Randy?

My apologies to all the other Randy's out there! I was hoping the context was covering my lack of detail!

 

[lavoisier]

I had similar issue when calibrating mine recently. Read 43ppt no matter what I did. This is how I fixed mine. Credit to @rkpetersen in this thread

Apex salinity probe calibration

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...

www.reef2reef.com

-Remove probe from apex
-Make a fake calibration (manual, so just go through the steps quickly and finish it)
-Reboot your apex (I just unplugged mine)
-Reconnect probe
-and do MANUAL calibration with the packet (make sure no micro bubbles on the probe, etc)
That fixed it for me. maybe it helps you.

Worked like a charm.