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Thread: pH increases after heating

  1. #1
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    Apr 2013
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    Pune, Maharastra, India
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    pH increases after heating

    Dear water chemists,

    I am running into a strange issue. My RO water which i'm slightly blending with the raw water (after carbon and sediment filter) shows a pH of 7.1-7.2 which is what I want. Now when I heat it up the pH seems to be shooting up to 7.9-8.0. I thought it was a problem with my HLT and so I took a small sample and heated on the stove to check. Got similar results.
    Ca 10
    mg 4.1
    Cl 26
    SO4 1.8
    HCO3 68
    Na - unknown
    Alkalinity 56.2
    total hardness 42.4

    What could possibly going wrong and how can I fix this?
    When I stop blending the water pH is too low 6.5

  2. #2
    Join Date
    Oct 2002
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    I suspect you are converting the bicarbonate to carbonate during the heating process, which isn't hot enough to remove the carbonate fully.

    However, the key question is, with this water, what are your mash (and subsequent wort and beer) pHs like?

    I strongly suspect that by the time you have added the grist, you won't notice a thing, because there is going to be so little buffering capacity in the water compared to the grist materials. providing your mash pH is OK, and subsequently you wort pHs throughout the rest of the process, I wouldn't get too hung up about a small amount of carbonate. Plenty of good beers have been brewed with slightly alkaline water.

    If your pHs and flavours are as you want, stop worrying and don't waste money and time on further water treatment
    dick

  3. #3
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    Quote Originally Posted by dick murton View Post
    I suspect you are converting the bicarbonate to carbonate during the heating process, which isn't hot enough to remove the carbonate fully.

    However, the key question is, with this water, what are your mash (and subsequent wort and beer) pHs like?

    I strongly suspect that by the time you have added the grist, you won't notice a thing, because there is going to be so little buffering capacity in the water compared to the grist materials. providing your mash pH is OK, and subsequently you wort pHs throughout the rest of the process, I wouldn't get too hung up about a small amount of carbonate. Plenty of good beers have been brewed with slightly alkaline water.

    If your pHs and flavours are as you want, stop worrying and don't waste money and time on further water treatment
    Thanks Dick,
    The mash pH is now reaching 5.6-5.7 sometimes 5.8 - I am adding 40-50 ml of Phos acid to bring down the pH. All the beers that we are brewing are now reporting slightly higher pH. What worries me is also the last running pH now bordering at 5.9-6.0 which again we know isn’t good.
    Should I stop blending the water ? I boiled the water once prior to brewing instead of just heating. But the end results were same.

  4. #4
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    Oct 2002
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    Both the mash pH, and final wort runoff pH are far to high for optimum enzyme activity (you are measuring it at 20 deg C aren't you?)

    So depending on what you are brewing, you may want / need to add more acid to the brewing liquor or mash itself, and to the sparge water. You really shouldn't be exceeding 5.4 at end of wort runoff.

    I would also add some calcium chloride to the grist, to achieve about 100 ppm calcium - though others not unreasonably would say just acid treat, on the basis that some pilseners are brewed with very low calcium levels. However, my experience is that although this is true, in a simple mashing system I prefer to have about 100 ppm minimum Ca, which precipitates phosphates and oxalates in the mash - releasing hydrogen, and so reducing the pH. Having precipitated the phosphates and oxalates, they are then not left in the beer to cause hazes in the final beer - we used to have amazing "snowstorms" of (mainly) oxalate particle in a couple of beers because the licensing brewing spec said don't add calcium - but we changed that and on adding calcium to the mash - we had no more snowstorms. If you get you beer analysed, providing there is about 25 ppm Ca left in the beer, then you will normally have better haze stability, and better yeast precipitation at end of fermentation. Of course, if brewing ales, you may want higher levels than that, associated with higher levels of chlorides and or sulphates to give particular flavour characteristics to the beer
    dick

  5. #5
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    What is the temperature of the water when you are measuring pH? It is temperature dependent and needs to be corrected, some pH meters do this automatically, some don't.

  6. #6
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    I am currently measuring pH at 20 C we have to manually adjust the pH meter to desired temps.

    I am adjusting the salts based on the style.. this water brews a Stout better than any other ale we make.. due to its alkaline nature. I donÂ’t necessarily aim for 100 ppm Ca but use a highly flocculant so4 Fermentis for major styles .. so far no issues with Haze nothing that Biofine cannot clear.. I guess I have another option to add lactic straight to mash or use acid malt.. since phos acid can also remove Ca from water.

  7. #7
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    Nov 2002
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    Columbus, OH
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    pH meter

    You calibrate your pH meter each time you use it (or regularly at least)? Also, how old is the probe? Store it in buffer solution? With that alkalinity and harness i'd expect your water pH AND your mash pH to be much better....Also, why are you ROing that water? ....it sounds pretty good
    Larry Horwitz

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