pH toooooo low!

Discussion in 'Reef Chemistry by Randy Holmes-Farley' started by d2mini, Feb 5, 2018.

  1. GoVols

    GoVols "VFL" R2R Supporter Reef Squad R2R Excellence Award MTRCMember Reef Tank 365 Article Contributor Build Thread Contributor Partner Member 2018

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    M,
    I almost bought the Abyzz A100 DC, but I got a GEO cal reactor instead.

    Talked to Klaus at Royal Exclusiv and they have new DC's in the works, and they are beta testing them, right now.

    Freddie
     
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  2. bubbaque

    bubbaque Never enough SPS R2R Supporter Build Thread Contributor

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    Dennis, watch the temp of the cup. Temp will affect the ph reading also
     
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  3. Want2BS8ed

    Want2BS8ed Active Member R2R Supporter

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    Hear that! Gotta do what you gotta do... good to hear Royal is working on some new DC pumps. Hopefully the competition at the top end of the market will bring prices down.

    Meanwhile, the replumb on the skimmer intake is done. Hopefully the picture below makes sense.

    It will take about 3 weeks to see if it made an appreciable difference in the life of the media, but I'm pleased with how it turned out.

    M
    [​IMG]
     
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  4. Brew12

    Brew12 Electrical Gru R2R Supporter R2R Excellence Award Reef Squad Leader Article Contributor Build Thread Contributor Partner Member 2018

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    I'm still baffled by this. It just isn't making sense in my pea brain. Its almost like it isn't a pH sensor plugged into the pH port. :confused:
     
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  5. GoVols

    GoVols "VFL" R2R Supporter Reef Squad R2R Excellence Award MTRCMember Reef Tank 365 Article Contributor Build Thread Contributor Partner Member 2018

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    Looks great!!!
     
  6. d2mini

    d2mini Moderator Staff Member Team R2R R2R Supporter R2R Excellence Award Photo of the Month Award Article Contributor Build Thread Contributor

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    UPDATE:
    The cup was outside this morning with a small pump circulating the water from 8am to 12 noon.
    Temps were about 67-68 when I took it inside and shoved the pH probe in there.
    The pH topped out at 7.85

    I put the cup back outside and will retry later this evening.

    Anyone know what kind of effect the 10 degree difference in water would have had?
    Still seems pretty low to me though.
     
  7. Brew12

    Brew12 Electrical Gru R2R Supporter R2R Excellence Award Reef Squad Leader Article Contributor Build Thread Contributor Partner Member 2018

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    The temp compensation would be less than 0.1.

    You have a pH probe issue.

    Edit: Actually, before I put my foot in my mouth with a statement like that... what is the alkalinity of the sample?
     
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  8. Randy Holmes-Farley

    Randy Holmes-Farley Reef Chemist Staff Member Team R2R R2R Supporter R2R Excellence Award Article Contributor Expert Contributor

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    The temp effect on measured pH is complicated and is actually caused by different things.

    The probe itself varies in its output as a function of temp, and the effect is zero at pH 7.000 and gets larger the farther you are from pH 7. Essentially, the slope of the mv vs pH response changes.

    here's a calculator for that part of the effect:

    https://www.hamzasreef.com/Contents/Calculators/PhTempCorrection.php

    A second effect has to do with how the pH changes the pKa of the main buffers in the solution. In seawater, bicarbonate is the main acid present in the buffer system, and it is a stronger acid as the temp is raised. It's pKa goes from 6.1 at 0 deg C in seawater to 5.7 at 40 deg C in seawater. That pH shift will tend to reduce pH (a measure of H+) as the temp is raised because more HCO3- will ionize to H+ and CO3--. This is part of the reason why there is more precipitation on warm heaters and pump impellers: because carbonate is locally higher than at cooler temps.
     
  9. d2mini

    d2mini Moderator Staff Member Team R2R R2R Supporter R2R Excellence Award Photo of the Month Award Article Contributor Build Thread Contributor

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    When i took it out of the tank this morning, it was 8.5 dkh
     
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  10. Brew12

    Brew12 Electrical Gru R2R Supporter R2R Excellence Award Reef Squad Leader Article Contributor Build Thread Contributor Partner Member 2018

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    Show off! :p

    I'll stick with the less than 0.1 ;)
    Yup.. pH probe issue.
     
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  11. Potatohead

    Potatohead Well-Known Member

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    Just buy a new probe already lol. You're going to need it eventually anyway.
     
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  12. Brew12

    Brew12 Electrical Gru R2R Supporter R2R Excellence Award Reef Squad Leader Article Contributor Build Thread Contributor Partner Member 2018

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    You use Profilux, right? Is the pH probe you used the one with your Profilux system?
    And it calibrates ok?
     
  13. Want2BS8ed

    Want2BS8ed Active Member R2R Supporter

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    durn... you had me when you said it was 68 degrees this morning!
     
  14. Brew12

    Brew12 Electrical Gru R2R Supporter R2R Excellence Award Reef Squad Leader Article Contributor Build Thread Contributor Partner Member 2018

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    If it is Profilux, take a look at your pH calibration data. Here is mind from myGhL. Your numbers should be fairly similar.
    upload_2018-2-9_13-20-58.png
     
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  15. d2mini

    d2mini Moderator Staff Member Team R2R R2R Supporter R2R Excellence Award Photo of the Month Award Article Contributor Build Thread Contributor

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    This weekend!

    Yes, the Profilux seems to calibrate it ok. But this is not an original probe. I think this one was a BRS probe.
    Probably a year old this month if it is the one i bought from them.

    It was 54 at 5am and headed to 72 today!
    But back to a high of 42 this sunday. ;Nailbiting
    I've been miserable all winter.
     
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  16. d2mini

    d2mini Moderator Staff Member Team R2R R2R Supporter R2R Excellence Award Photo of the Month Award Article Contributor Build Thread Contributor

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    Huh... never paid attention to that before.
    Mine are...
    7.0
    386
    9.0
    185
     
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  17. GoVols

    GoVols "VFL" R2R Supporter Reef Squad R2R Excellence Award MTRCMember Reef Tank 365 Article Contributor Build Thread Contributor Partner Member 2018

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    Heck,
    We're at 65 degrees in Nashville today, and our town home's windows are up.

    [​IMG]

    :)
     
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  18. Want2BS8ed

    Want2BS8ed Active Member R2R Supporter

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    Need to make a quick correction, the McMaster-Carr valve (part #5489T493 w/ 3/8" quick connects) is 24v, not 120v as originally stated.

    It's hooked to and controlled through the 24v accessory outlets on Neptune's Apex EB832 energy bar.

    Sorry if that caused any confusion.

    M
     
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  19. Brew12

    Brew12 Electrical Gru R2R Supporter R2R Excellence Award Reef Squad Leader Article Contributor Build Thread Contributor Partner Member 2018

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    That actually looks pretty good as far as spread goes. If you ran with my calibration data your pH would look good! :p

    I just don't understand why your calibrates to a proper ranged spread but reads so low. When you finished calibrating it, did you retest it in the solutions?
     
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  20. d2mini

    d2mini Moderator Staff Member Team R2R R2R Supporter R2R Excellence Award Photo of the Month Award Article Contributor Build Thread Contributor

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    No, I did not.
     
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