The Easy Way To Hit The Proper Boil pH


This wort is coming to a boil. Already you can see a small amount of break material has formed.

When most homebrewers consider pH in brewing, they think about achieving the proper mash pH. However, hitting the proper boil pH (of 5.1–5.2) is also important. Having wort in the right pH range at the end of the boil has a few benefits, most notably better hot break production. As wort pH decreases, there is also less color pickup in the boil and hop bitterness becomes more pleasing, although hop utilization decreases.

Sometimes (perhaps most times), having an ideal mash pH of 5.2–5.6 will ensure that your boil pH drops into the proper range without any intervention by the brewer. However, this is not guaranteed. Two different unboiled worts can start at the same pH, but end up at different post-boil pH levels, even if they are boiled for the same time and at the same intensity. Most often, if the boil pH is out of range, it is too high.

Fortunately, there is an easy way to check on your boil pH and adjust it — all without requiring a pH meter or anything you don’t likely already have in your brewery.

Below a pH of 5, the coagulation of proteins decreases. (Hot break, the light-colored flakes that form in your kettle during the boil, is coagulated protein.) Above a pH of 5, the amount of protein coagulated is constant, but the break material looks different at different pH levels. At a pH of 5.2, hot break is seen as relatively large, fluffy flakes floating in otherwise clear wort. In some cases, these flakes may even clump together into larger “globs” of break material. The farther you move away from a pH of 5.2 (in either direction), the smaller hot break particles become. A few tenths of pH point away and the wort may simply look cloudy. So, you can use the presence or absence of big, fluffy hot break flakes as an indication of whether or not you are in the right boil pH range. The malts you use also effect the appearance of the hot break. Their protein levels and amount of protein modification achieved in malting also play a role.

The same chemical reactions, primarily between calcium and phosphates, that help a brewer establish the correct mash pH can also help him or her establish the proper boil pH. If your boil is cloudy, but large flakes of break material are not present, the problem is likely that your boil pH is too high. Adding a small amount of calcium will fix this problem most of the time. Plus, you will be able to tell if it worked by the appearance of large, fluffy flakes in your kettle.

So here’s how to hit the right boil pH in most ordinary brewing circumstances. If, after the first 15 minutes of boiling your wort, you think your boil pH is too high, add approximately 50 ppm of calcium ions to your kettle. For 5 gallons (19 L) of wort, adding 1 tsp of calcium chloride (CaCl2) or calcium sulfate (CaSO4) will yield about 50 ppm. After another 10 minutes, check your wort again — if the break material still seems like little specks as opposed to bigger flakes, add another 50 ppm of calcium.

Most of the time, you’ll see your hot break improve after the first addition. If two additions of calcium don’t work, adding more calcium is probably not going to solve the problem. Finally, if you do have a pH meter, you can also measure your wort pH in the final 15 minutes of the boil, and adjust it with acid (such as phosphoric acid) to a pH of 5.1–5.2, if needed.



  1. Tim Jordan says:

    Why is a better hot break important? What does that do for the beer?

    • Chris Colby says:

      Coagulating the hot break and separating it from the wort after chilling yields a wort with fewer proteins in suspension. The resulting beer will also have a lower protein level and be less susceptible to chill haze, which is formed when proteins and tannins come together in chilled beer. It will also be more biologically stable — i.e. contaminants (beer-spoilers) will have a harder time growing in it without the nitrogen found in proteins.

      A good hard boil at the right pH, and a little Irish moss or whirlfloc, will leave you with a wort with enough proteins for yeast health and foam formation, but not so many as to make the beer likely to form chill haze. (Quick wort chilling so you form a good cold break also helps.)

  2. How would you recommend adjusting your boil based on the information here? If we notice we aren’t getting big, fluffy hot break, is there an easy way to tell if our pH is high or low? I’m thinking we would need colorphast strips or a pH meter to make sure we don’t drop the pH when we need to raise it.

    Great article!

    • Chris Colby says:

      The thing is, if your boil pH is off (as indicated by tiny specks of hot break in your kettle, not larger flakes), it is most likely going to be high. Unless you added something to the kettle that was acidic (like fruit), you’re much more likely to be over the optimal pH than under. So, if your break doesn’t look as good as it should, add some calcium. In almost every “normal” circumstance, you’ll move the pH in the right direction. If you think your pH might be too low, then you should invest in a pH meter because something out of the ordinary is going on.

      • That’s good info. I should have realized the pH would probably high. I wish I would have checked on this before I brewed yesterday. My pale ale had a lot of small, flaky hot break. I could have tried adding calcium.
        Oh well, now I have an excuse to brew again!

  3. Great info. I love simple rule of thumb techniques that don’t require the purchase or building of yet more brewing equipment. PROST!

  4. Why not lactic acid instead of calcium for pH reduction in the boil?

  5. Dave Laux says:

    Is it safe to assume your pH values are taken at room temp?

  6. Thanks for the article., very instructive. We use to add 6 grams of gypsum to the boil as routine (6,8 gal batch), because of we have read in Graham Wheleer’s Brew Your Own British Real Ale that it will improve calrity, stability and yeast performance. But we did’t know why…. You said that the calcium addition you choose between addin calcium sulfate or calcium chloride. Will this decission afect the chloride/sulfate ratio, and the final taste of the beer?

    • Chris Colby says:

      This adds calcium and either sulfate or chloride, depending on which mineral you add, to your wort. So, the ratio is changed a bit. If you are worried about the ratio, you can add either gypsum (calcium sulfate),, calcium chloride, or a combination of the two to preserve the chloride to sulfate ratio.

  7. Jay Waldner says:

    Nice article with good information. However, my issue seems to be having too low of a boiled wort pH, i.e. less than 5. My pre-boil pH seems appropriate though. What could be causing this? What effects could this have and how can it be corrected? Thanks

    • Chris Colby says:

      A post-boil pH that is too low is uncommon. I am not sure what might cause this. (As always, I would make doubly sure your pH meter is calibrated.) One possible negative side effect of low pH would be incomplete hot break formation.
      How low is the pH ?

  8. It appears Chris Colby is confusing “hot break” with “cold break.”

    Hot Break is what precipitates during the boil and
    is removed normally by whirlpooling a few minutes after boiling or via a hop filter. Hot break is not desireable in the fermenter.

    Cold Break precipitates during rapid cooling of the wort and is beneficial to yeast as it provides nutrients for the yeast. Tests have demonstrated that leaving the cold break in the fermenter does not impact beer clarity or flavor.

    • Chris Colby says:

      I have not confused them. The article discusses only hot break. I don’t even mention cold break, or the implications of carrying over break material to the fermenter. [Also note that most homebrewers use immersion chillers, so hot and cold break — along with hop debris — is mixed in the bottom of their kettle after chilling. Brewers who use counterflow or plate chillers can leave their hot break behind in the kettle and deal with (or not) their cold break in the fermenter.] In any case, what I wrote only addresses the effect of pH on hot break formation in the kettle.

  9. Hello Chris,

    Thanks for a great intuitive article. This has got me thinking, if I was brewing a pale lager as I have soft water, wouldn’t adding sulfates and chlorides to help with my boil ph affect the flavour and ill end up with a Minerally lager. Are their safe upper limits on chloride and sulfates I should watch out for without going overboard. FYI my tap water is very soft. Thanks

  10. Colin Kaminski says:

    There is an old brewer’s rule of thumb from ale brewing. Add half of the minerals that you added to the mash in boil.

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