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CO2 measurement and revolution, KH referenced pH probe

Discussion in 'CO2 Enrichment' started by Tom Barr, Dec 1, 2006.

  1. Tom Barr

    Tom Barr Founder
    Staff Member Administrator

    Jan 23, 2005
    Likes Received:
    Local Time:
    1:43 AM
    Using similar methodology from dissolved Oxygem meters and adaption of Vaughn's KH reference solution inside a drop checker, I've taken the more accurate pH probe approach to resolving the wide ranges of CO2 ppms that the pH/Kh/CO2 table often give folks.

    I wonder how folks mange that use ahem, O2 membranes, that
    measure O2 and their response times?

    You'll note, that I suggested to place the probe near flowing
    water, much like the DO probes.

    I think George Booth is perhaps the only one besides myself that
    has a DO meters and is prepared to use it:)
    Not sure why I did not think of that eailer dammit.

    It also is very effective at determining if one vs another
    method/treatment produces better plant growth than another(such
    as CO2 mist vs dissolved). I have a O2 difference of about
    3-4ppm at 29 C. So there's the evidence for that. Now I'll go
    back and get a very accurate CO2 measure.

    Of course what the hell do I know, I'm always telling folks not
    to test and to watch their plants and take good care of their
    water changes/dosing. haha

    The two main types of membranes are sealed caps and loose films+
    O ring gasket.

    But here's a neat idea:

    If we could get the "guts" removed from a sealed DO probe
    version and add a pH probe in it's place, then add the KH ref
    solution instead of the KCL electrolyte solution that normally
    goes in the DO probes, then it would be ideal.
    Basically use the outside seal/housing of the DO probe and the
    nice threaded membrane cap but with a pH probe instead inside.

    Teflon is pretty good about fouling.
    The poly membranes are more prone to fouling but better and more

    Simply storing the probe tip in a KCL solution every few days
    etc will prevent the membrane from becoming fouled up.
    So stop all that crying about biofouling:)
    You can carefully wipe the membrane peroidically as well(the
    teflon types)

    This is a simple method and is more responsive than I thought
    eariler. A little tweaking and I can get a real nice set up.

    I'm going to bug Pinpoint and Milwaukee to see if they can make
    a sealed screw on cap type probe like the DO version, but with a
    0.01 accuracy pH probe inside.

    That way I can use the nice screw on seal with the membrane
    already on there and conveinence of their probes, they are cheap
    as well.

    I'll still need to take the pH probe out to calibrate it and add
    KH ref solution back.

    Then I'll go back and redo some Mist vs Reactor measurements to
    see if there is a significant difference using very accurate
    measurements for both CO2 and O2 together.

    From there, I can make some rather strong statements as to O2
    and CO2 levels in our tanks with a higher degree of confidence
    and less assumptions.

    And then so can others.
    Vaughn has already laid the ground work for folks using the Drop
    checker method, a much cheaper version and also very good for
    the less techy folks.

    Tom Barr

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