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Thread: salinity probe reading wrong

  1. #51
    Frequent Contributor zombie's Avatar
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    Quote Originally Posted by Bobbydigital View Post
    On my dashboard what number should I be looking for. 30-35 right? If it says 57 it’s way to high right. My refractometer says I’m at 30ish
    You need to recalibrate if its showing that high. A properly calibrated probe should read within about 1-2ppt or so of a properly calibrated refractometer. Due to how far off it is, I would "reset" the probe first my quickly scrolling through next on a manual calibration with the probe unplugged.

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  2. #52
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    Thanks the reset worked it’s reading about what my refractometer is showing.

  3. #53
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    Are you using the automatic or manual calibration method?
    I have found the auto to be way off no matter how many attempts. By manually calibrating-not exactly matching but much closer off by 2 ppt.


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  4. #54
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    I used auto. It’s working good now. Thx

  5. #55
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    I about gave up on mine. I would calibrate it, it would be good, then drift to an unrealistic level over weeks (like 45ppt). I stopped wasting money on solution, didn't trust it and just calibrated it with tank water every couple weeks. Since I keep my tank at 35ppt, that is basically equivalent to the 53,000us solution. I just checked with refractometer first. After a couple months the probe became much more stable. It will hold calibration and not drift continually. I went back to calibrating with solution (always manual on all probes, let them soak 10 minutes!) About the only weird thing it does now. It will read 35ppt (+/-0.2) for 12-24 hours, then it will shift to around 35.5 or 34.5 (+/- 0.2) for a couple hours and then return to 35 (+/- 0.2) for another 12-24 hours. Some of this I have been able to correlate to events. Like if I open up my stand and take off my sump lids for a couple hours it will shift 0.5 up, but eventually return when everything is back together. Other times it might shift 0.5 and I didn't do anything and I cant find anything in logs to explain it. Usually it shifts down by 0.5 unexpectedly. Based on these observations I'm guessing: The probe needs to "break in" for months. It is sensitive to ambient air fluctuations. Possibly the short unexplained excursions are caused by condensation inside the probe barrel, since it is pure water maybe it drips down and lowers conductivity (salinity) temporarily. I moved it lower in the water and that does seem to help both, less air exposure and less room for condensate to form. I have heard the tops can become brittle if constantly submerged, so I keep them a little out of water normal level.

    I know this might be frustrating to hear. I expected it to work perfect out of the box too. I thought it was worthless after even a couple months. I'd still never use it to determine the level of adjustment for salinity. I do however find it useful now to see if I should get out the refractometer. To stop an ATO and alarm. If I was away and had a sump sensor level or wet floor alarm, I could use it along with other logs to figure out what might be happening and how bad it might be. Also I keep in mind that accuracy, precision, resolution are all very different. They can be combined into measurement uncertainty. This is what calibration and metrology labs are rated by. NIST probably has a 10 million dollar machine to measure conductivity better than anyone on earth. Our calibration packets are rated to +/- 1% to NIST. Our $600 apex head and probe adds a lot more. Our house voltage, temperature, wire connectors, fish poop, etc.. all adds uncertainty. A system to do it better would not be affordable. A good refractometer is fairly cheap and it is more accurate and has a lower uncertainty because it is less complicated and has fewer contributors to uncertainty. It is more of a direct link to a solution traceable to NIST.

  6. #56
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    Saliity example.JPG

    This is a good example of what I see sometimes (from today actually). Couple hours of noisy signal trending low, several hours of more stable signal, couple hours of noisy signal trending low. Nothing correlates to this on my tank, pumps, heaters, lights, temps... It might be my house electricity noise, who knows. I'd expect that to be worse during daytime though. I see this behavior often and it seems totally random, sometimes it is mid day, sometimes the noise trends up.

  7. #57
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    Quote Originally Posted by Diznaster View Post
    Saliity example.JPG

    This is a good example of what I see sometimes (from today actually). Couple hours of noisy signal trending low, several hours of more stable signal, couple hours of noisy signal trending low. Nothing correlates to this on my tank, pumps, heaters, lights, temps... It might be my house electricity noise, who knows. I'd expect that to be worse during daytime though. I see this behavior often and it seems totally random, sometimes it is mid day, sometimes the noise trends up.
    Did you contact Neptune support? I had a similar issue, they asked me to send photos of the salinity probe port on base unit, they they said the port was "recessed" and would be replaced. Waiting for my replacement now

  8. #58
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    Thank you this helped me solve the issue after 3 days of support trying to put blame at everything else, it was the APEX salinity port or calibiration settings that just needed to be reset.
    Quote Originally Posted by zombie View Post
    You need to recalibrate if its showing that high. A properly calibrated probe should read within about 1-2ppt or so of a properly calibrated refractometer. Due to how far off it is, I would "reset" the probe first my quickly scrolling through next on a manual calibration with the probe unplugged.

    Sent from my SM-G965U using Tapatalk

  9. #59
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    Sorry to bring back a thread that may be old but I am having some issues with calibration as well. I have calibrated my conductivity probe and it is measuring 34.2 while in the solution pouch at 77.5F which should be correct from what I am reading. However when I place the probe in tank water it reads 22.7. I have double checked my water parameters with a refractometer and hanna checker that were both calibrated before checking as well and both read 1.025 and 1.026 respectively. Did I miss something in my calibration?

  10. #60
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    Thats a huge change. My first guess is maybe a stray voltage from a bad heater or something. Can you fill a jar with tank water and test it that way?

    Edit: I see it's your first post, is your probe new? Honestly don't even try to calibrate it or trust it until it has been in your tank for a couple weeks. I don't understand why this happens but it is common. Mine was all over the place for a few weeks when it was new. After that it's been pretty solid for a year now, it trends with my refractometer so I really don't calibrate it much either. I just use it as data point in case maybe something in the ATO went haywire, etc..

  11. #61
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    Checked in a separate container and only small change. 23.4. Could it be just an old pack of solution? I’ve had it a while but never opened. I don’t see how that could make it read correct in solution but off in tank when it should be close to same.

  12. #62
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    You eliminated stray voltage, so that's good. I edited above, is the probe new?

  13. #63
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    No probe is old maybe 2016 or 17. I bought it new from bras at the time.

    i had taken down an old tank but kept my live rock and probes running in a small tank until I got this one up. Honestly I haven’t really played with it much over the past year.

  14. #64
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    So it has been in tank water for a couple years, but is now suddenly acting weird?

  15. #65
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    It’s probably been out of calibration for a while because I just had it in a small tank to keep it wet for a long time with my rocks

  16. #66
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    Maybe try an hour+ vinegar soak with a good RODI rinse. Then do a calibration but just use tank water (don't waste a packet). See if it stays stable. If not the probe might be bad?

  17. #67
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    I’ll try that tomorrow after work. After the RODI rinse should I let it thoroughly dry before trying to calibrate or just go for it with the tank water

  18. #68
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    The other common problem besides electrical interference is bubbles in the probe. Try submerging it upside down so the bubbles can escape upwards out of the end of the tube.

  19. #69
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    Quote Originally Posted by Vaelr View Post
    Sorry to bring back a thread that may be old but I am having some issues with calibration as well. I have calibrated my conductivity probe and it is measuring 34.2 while in the solution pouch at 77.5F which should be correct from what I am reading. However when I place the probe in tank water it reads 22.7. I have double checked my water parameters with a refractometer and hanna checker that were both calibrated before checking as well and both read 1.025 and 1.026 respectively. Did I miss something in my calibration?
    Manually calibrate probe.
    Step 1. Put probe out of water.
    Step 2. Go to salinity probe calibration and select manual calibration.
    Step 3. Click continue until calibration is complete.
    Step 4. Send update to apex.
    Step 5. Now calibrate for real but with automatic. Then send update.
    Step 6. Put probe back in aquarium and all should be good.

    This has happened only twice to me and as long as I manually reset it it's gone back to normal immediately after these steps. I think apex might have quietly released a fix though because it has been quite a few months since it has gone off like that and I did update apex after.

  20. #70
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    So I tried what diznaster suggested. Did a vinegar soak and rinsedwith RODI. Then did a calibration using tank water. Reads between 34.6 and 34.8 since last night. Do you think I should order a few more packets os solution and try to recalibrate with them after a few more weeks?

  21. #71
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    Quote Originally Posted by Vaelr View Post
    So I tried what diznaster suggested. Did a vinegar soak and rinsedwith RODI. Then did a calibration using tank water. Reads between 34.6 and 34.8 since last night. Do you think I should order a few more packets os solution and try to recalibrate with them after a few more weeks?
    I recommend you try what I said. It was told to me by Neptune and has worked every single time.

  22. #72
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    Ok. But how do you do the manual calibrate?

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  24. #74
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    I’m using an apex classic. I don’t have the advanced.

  25. #75
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    Quote Originally Posted by Vaelr View Post
    I’m using an apex classic. I don’t have the advanced.
    You have it but only on the local dashboard not in fusion.

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