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  • Author Author: m.ratcliffe
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Automated Green House Blog:13.9 - PH Probe Revival: Ultrasonic Cleaning

m.ratcliffe

In Aquaponics systems pH probes fail quickly, it is my belief that this is due to the probe membrane becoming blocked [just my theory, no proof to back it up]. If this is indeed the problem it stands to reason that we could extend the probe life by cleaning the probe during the monthly calibration.

 

There are two main ways to clean the glass probe:

>Mechanically

>Chemically  [See link below for selecting the correct chemical for your probe use]

http://reagecon.com/pdf/technicalpapers/Electrode_CM_v5_TSP-02_Issue_4.pdf

 

I like to keep my stock of chemicals to a minimum so he mechanical methods are more desirable to myself, in particular ultrasonic cleaning.

 

 

 

 

 

 

The Test:

>Verified probes where faulty [either fluctuation or slow response time]

>Clean with toothbrush and then place in ultrasonic cleaner for 6 -10 minutes

>Recalibrate and verify fluctuation and response is similar to new probe

 

The Results:

>50% success rate [4 probes tested] [Thanks for bringing this method up DAB]

note: Some of the probes may have failed by something other than blocked membrane

 

 

Keep an eye on the main blog for Updates, future updates on the pH portion are:

>Self aware code for arduino that will check for faulty probes as part of calibration routine

>A 3D printed probe cap and filter design that may increase the life of pH probes in aquaponics

>pH controller, all open source as always

 

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  • in reply to m.ratcliffe

    The article I read did not elaborate.

    I assumed they were discussing salt crystals which would be the logical formation with acid and base solutions interacting.

     

    Protein buildup would be caused by biological/chemical compounds forming in the area where the ions are exchanged from the fluid and the probe.

     

    One thing was clear, you need to clean the probes carefully after every use to minimize the buildup of unwanted material.

     

    DAB

  • in reply to DAB

    Could you expand on the crystals part DAB,are they on the inside or the outside of the cell membrane?

    Ive not read too far into it but another failure is proteins blocking the membrane.

  • Nice update.

     

    As I understand the probe description, the solutions inside the probe establish an ionization potential between the tested solution.

    This ionization potential can cause crystals to form in and around the probe, insulating it from the tested solution.

     

    The manufacturers claim that each time you use the probe, you need to thoroughly clean the tip with deionized and distilled water.

    Please note, deionized water is different from your run of the mill distilled water.  They use a special filter that removes any ions that tend to collect in the water from contact with charged substances.

     

    The recommended ultrasonic cleaning is intended to disrupt the crystals, which should then react with the deionized water for removal.

     

    Hopefully my research into atomic structures and chemical compounds will enable me to better understand how the probe works and perhaps suggest simpler methods for measuring Ph.

    Until then, you are stuck with what you can buy.

     

    So make sure clean your probes with every use or they will quickly degrade.

     

    DAB