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  • Can no longer seem to hone mash pH

    Hello all,

    We've been brewing along without any issue for a few years, but we've suddenly found that we're having great difficulty honing in our mash pH. We can't seem to target anything below 5.6pH, even with generous additions of Phosphoric Acid (direct to HLT) and "overdoing" our mash salts (pre-solubilized CaSO4 and/or CaCl added throughout dough-in). Our instruments are calibrated, and we have recently re-passivated our HLT.

    We use the Bru'n Water spreadsheet to calculate our acid/salt additions. Our incoming water is only treated with a catalytic carbon filter.

    Most recent water report:

    Calcium: 16ppm
    Magnesium: 10ppm
    Sodium: 18ppm
    Bicarbonate: 51ppm
    Carbonate: 5ppm
    Sulfate: 30ppm
    Chloride: 34ppm
    Total Alkalinity: 54ppm

    We will sometimes dough-in with mash water pH at 6.2, but this seems to have no significant effect when compared to mashing in at pHs between 7.0-8.0.

    We're at a bit of a loss -- any guidance on what we might be overlooking would be very appreciated.

  • #2
    How old are your pH calibration solutions? Have you performed a stability test on the pH meter and probe.

    The alkalinity level in that water isn't extreme and it should not take a lot of acid to neutralize. Are you sure of the acid's purity and strength?
    WaterEng
    Engineering Consultant

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    • #3
      pH meters don't last forever. Even if your buffer solutions are OK, the meter (normally the probe itself, if separate to the box of electronics) deteriorates and needs to be replaced.
      dick

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      • #4
        Thank you both -- although my buffer solutions were within their efficacy dates, grabbing some fresh solution was the key to getting my equipment properly calibrated. I'll definitely make it SOP to have smaller amounts on-hand in order to more often cycle through them. Cheers!

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        • #5
          pH Meters should be calibrated at least once on each brew day. Those 500 ml bottles of calibration solution should get used up in a reasonable amount of time and avoid expiration with that calibration frequency. I find that if you use the industry-standard, cabled pH probes that have a nice small probe diameter (say half-inch), you can pour the calibration solution into the calibration solution bottle's cap and immerse the probe in there. Of course, that used solution should be thrown out after its touched the probe for calibration. This ability is one of the reasons why the all-in-one probe/meter units aren't that great for commercial use. Using a good commercial meter with industry-standard, cabled pH probe is the best option for any brewery.
          WaterEng
          Engineering Consultant

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          • #6
            I've had a different SOP...

            Using the cap for calibration would keep the cap off the bottle. I always keep the cap on the bottle. Not only for calibration solutions, but especially for reagents like NaOH. These solutions seem to lose accuracy fairly quickly. I've seen other folks use Parafilm on the caps during storage as well.
            Phillip Kelm--Palau Brewing Company Manager--

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            • #7
              Originally posted by gitchegumee View Post
              Using the cap for calibration would keep the cap off the bottle. I always keep the cap on the bottle. Not only for calibration solutions, but especially for reagents like NaOH. These solutions seem to lose accuracy fairly quickly. I've seen other folks use Parafilm on the caps during storage as well.
              Nope. The only calibration solutions needed in a brewery are the 7 and 4 solutions and neither of them suffer from short exposure to air. The 10 solution and other alkaline solutions like lye and lime will immediately be degraded by air contact. You're extrapolating incorrectly.
              WaterEng
              Engineering Consultant

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