Is my conductivity probe done for?

Discussion in 'GHL Advanced Technology' started by Be102, Jan 9, 2019.

  1. Be102

    Be102 Valuable Member

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    So over the past few weeks I have tried to really pinpoint my salinity levels by using my conductivity probe. At first a few months back I hooked up my p4 and then just basically set the probes up and that was it. Flash forward 7 months or so and I began to try to redo everything and actually get more use out of the p4. One of the most important aspects I felt was the ability to pinpoint my salinity levels to give me an idea on where my tank was standing at the time.

    I am having a hard time both getting an accurate reading and or just really having the probe stay still and not fluctuate. I have tried to calibrate it first with a tolerance of 1 and then with a tolerance of 2 thinking since it was in my tank for a few months maybe it has aged. Well now I am just stumped. the reading at this time in my tank reads at like 1.014- 1.016. This is way too low and no way my tank is at this level. It also says something similar when I make fresh saltwater at the correct measurements of 1/2 cup per gallon of water. ( instant Ocean). So now I have been determined to figure out where there problem is with this probe. @Ditto Suggested I put the probe in the calibration fluid after it was the same temp as the tank water and I did. It slowly climbed up to 50.ms but then it kept going up from there whilst sitting here typing this. its been sitting in the fluid for about 8 mins and it currently says 56.1 ms.

    What can be my problem? Is this normal? Theres just no way this fluid is gradually increasing unless it is and I wrong. I have no clue whats going on and have calibrated multiple times although it seems to always seem to be either really low and or seems to be a problem with my probe.. it is now reading 56.4 since typing this...
     

  2. sntmods

    sntmods Active Member

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    Did you thoroughly rinse in RO water, then clean and dry the probe prior to dipping it in the calibration fluid or did you immediately take it from the tank into the calibration fluid?
     
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  3. Be102

    Be102 Valuable Member

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    From on to another... Do you think thats the reason for the fluctuation or the inconsistency in my own saltwater results? Should I recalibrate it and make sure to do as you say for each part of the step?

    How sensitive are they for a decent cleaning? I seem to think of them as being very fragile so I tend to just wipe off with a rag inbetween the steps.
     
  4. sntmods

    sntmods Active Member

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    That may be a reason, yes.

    Also, are you placing the probe directly into the calibration fluid in the original container or are you removing some of the calibration to a different container so you arent contaminating the original fluid?
     
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  5. Be102

    Be102 Valuable Member

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    Container. I guess it could be contaminated but it’s always dry before going into the fluid. But I am still confused on why either I have low / inconsistent levels or why the fluid seems to continue to raise.. its over 62.4 right now still sitting in the fluid and rising.
     
  6. sntmods

    sntmods Active Member

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    I doubt that there is a problem with the probe or the profilux unit.

    The calibration fluid is likely already contaminated and I believe the climbing salinity is due to some salt deposits on the probe precipitating out.

    If you more thoroughly clean your probes as I've outlined above, you can even use a diluted white vinegar solution in addition to the RO water, and practice better calibration procedures; I think you'll find that you will have more consistent and accurate readings.

    Btw, I've also used canned air to remove any small water droplets that are sitting on the probe.
     
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  7. ispookie666

    ispookie666 Active Member

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    It is likely that your fluid has changed it's conductivity.

    I have found microbubbles to really throw off the reading, a vigorous shake of the sensor tip under water usually does the trick.

    If these are not the issues you have - the probe seems to be the next culprit.

    Ps: I have a P3
     
  8. kodo28

    kodo28 Active Member

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    Just buy another GHL solution and test the probe with solution at 25C your probe should read ~ 49.9ms ~50.00ms. If this is not the case then you are good to calibrate it .

    Make sure to keep the probe clean and dry before each time you put it into the solution.

    Temp of the solution inserted during the calibration process should also be really accurated.

    Cheers!
     
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