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Thread: Salinity reading keeps rising

  1. #26
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    Quote Originally Posted by zombie View Post
    Exactly.

    You might be an engineer if...You have no life and can prove it mathematically.
    Ok. That is also clearer to me. Cause I ordered calibration liquid and really plan to recalibrate the salinity Probe, even thought it seems to be more stable as I claimed, but still not totally accurate in reference to my refractometer.


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  2. #27
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    Quote Originally Posted by Tastee View Post
    Thanks for this thread, I am also having issues with my conductivity and PH probes since setting up my Apex a month ago. I originally calibrated as per the getting started guide which did not mention temperature stabilisation so I didn’t include that step. I have just picked up a pH 7 and pH 10 solution and are waiting for the conductivity solution to re-calibrate.

    At the moment my pH reads a little low and swings between 8.05 and 8.2, correlating with and lagging temperature changes (i.e. as temp rises pH also rises a short time later, as temp falls pH falls a little time later). My testing indicates pH is closer to 8.4 (API kit). Hopefully re-calibrating with a temperate matched solution will improve this.

    My conductivity reads a little high, as my refractometer shows a solid 1.024. Today at the time I took the refractometer reading the temp was 25.2 and the Apex read salinity at 36 ppt - should be closer to 34 ppt. It also bounces between 35.5 and 36.5, sometimes correlated with and lagging a temperature change. It also occasionally dives and then spikes, sometimes to 36.4 or so, sometimes to 36.8. The dive/spikes are typically caused by the chiller kicking in and dropping the temp from 26.5 to 25.2, but also occur when I do a tank clean. I currently have the temp comp set to 2.2 but I do see some inverse salinity changes compared to temperature changes so may need to try dropping this a little.

    I am not sure whether to recalibrate when I get my new solution or play around with it a little first before I do that. All my probes are located in the sump inlet of my Red Sea Reefer 250, above (and in) my Marine Pure balls, in a quite stable and air bubble free environment.

    Any suggestions or other thoughts would be greatly appreciated.
    Your welcome. I am still learning from everybody here as well.


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  3. #28
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    My original salinity probe was DOA and would never calibrate. Opened a case and got it RMA'd and replaced. I followed the calibration procedure and the probe kept showing about 2-3 points lower than my Hannah digital salinity monitor shows. Figured I would live with it but then the probe just started climbing. My chiller keeps the temperature pretty tight while the salinity probe just is going up and away. The Hannah shows exactly what I would expect.


    Screenshot_20180608-164239.jpg

  4. #29
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    Quote Originally Posted by masterxemu View Post
    My original salinity probe was DOA and would never calibrate. Opened a case and got it RMA'd and replaced. I followed the calibration procedure and the probe kept showing about 2-3 points lower than my Hannah digital salinity monitor shows. Figured I would live with it but then the probe just started climbing. My chiller keeps the temperature pretty tight while the salinity probe just is going up and away. The Hannah shows exactly what I would expect.


    Screenshot_20180608-164239.jpg
    That's normal the first couple days. It should level off 100% within a week and it probably 95% of the way there now. If you keep your tank at 35ppt, it looks like whatever mistake you made in calibration got canceled out by the soak in creep.

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  5. #30
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    When does it stop? It is at 36ppt today and still climbing. I keep mine at 35ppt. My digital refractometer still shows the correct salinity.

  6. #31
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    Check for stray voltage on your tank. It should have mostly leveled off the first day.

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  7. #32
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    What are typical raw data values when calibrating the conductivity probe? I have one that is less than 2 months old, and the salinity reading has been jumping upward over the past month. I've tried to recalibrate, but automatic calibration will not proceed due to an unacceptable dry value. The probe has been rinsed in RO, shaken and patted dry with a paper towel. Checking against my refractometer, salinity is fine, at 1.026, so it's not the water that is the issue.

    Manual calibration gives the following readings

    dry, 732
    53,000 us, 663

    Salinity now reads 39.3 with a raw data value of 776. As a chemist, this does not make sense, zero ppt salinity should be zero us, and dry should also read as zero us. I think my probe is shorted?

    Thanks,
    Attached Images Attached Images

  8. #33
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    The raw is not truly a raw number unless you first reset the probe (it's actually the current modified value in mS/cm). You can reset it by unplugging the probe and then quickly run through a manual calibration. Once reset the dry stage should be in the -50 to 100 range and the wet stage should be between about 500-700.

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  9. #34
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    Seems better now?

    Quote Originally Posted by zombie View Post
    The raw is not truly a raw number unless you first reset the probe (it's actually the current modified value in mS/cm). You can reset it by unplugging the probe and then quickly run through a manual calibration. Once reset the dry stage should be in the -50 to 100 range and the wet stage should be between about 500-700.

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    No stray voltage in the tank, don't use any internal pumps, have ground probes and regularly test for it.

    I did go ahead and go back and re-calibrate and it seems to have leveled out. Never actually intended too buy an Apex 2016 since I had an Apex Classic since it came out. But a few weeks ago the filtering cap on the power regulator in my Apex Classic shorted and ended up frying my Apex Classic (waaaaaaaaay out of warranty). So I had to go but a new Apex setup.

  10. #35
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    Quote Originally Posted by kylarse View Post
    What are typical raw data values when calibrating the conductivity probe? I have one that is less than 2 months old, and the salinity reading has been jumping upward over the past month. I've tried to recalibrate, but automatic calibration will not proceed due to an unacceptable dry value. The probe has been rinsed in RO, shaken and patted dry with a paper towel. Checking against my refractometer, salinity is fine, at 1.026, so it's not the water that is the issue.

    Manual calibration gives the following readings

    dry, 732
    53,000 us, 663

    Salinity now reads 39.3 with a raw data value of 776. As a chemist, this does not make sense, zero ppt salinity should be zero us, and dry should also read as zero us. I think my probe is shorted?

    Thanks,
    Turns out that the DIN connector was just coming loose. There are locking DIN connectors, maybe a product design change here?

    Probe re-calibrated fine after re-setting and re-seating the connector.

    Thanks for the assistance.

  11. #36
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    I had the same issue. After a water change the salinity went notes.
    Using the calibration salinity fluid fixed it.

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