Potassium and pH in Mead


Most light honey varieties do not have enough potassium to support a healthy fermentation. Darker honeys might. Musts made from either may benefit from having their pH adjusted to 3.6 to 3.9.

There has been an increase in the interest in meadmaking among homebrewers in the past decade. This is due in large part to Ken Schramm’s book, “The Compleat Meadmaker” (2003, Brewers Publications), which introduced the “dump and stir” method of making mead without heating the must (the unfermented honey mixture). Not too long after the publication of his book, meadmakers discovered that you could get a more ordered fermentation if you staggered the yeast nutrient additions. This allows the meadmaker to dole out the nutrients as the yeast need them rather than adding all the nutrients at the beginning of the fermentation, and this leads to faster, more ordered fermentations.

Recently, I spoke to Schramm about two other things that have come to light in recent years that are required for optimal mead fermentations — the need to give the yeast sufficient potassium during fermentation, and the need to control the pH of a mead fermentation. By happy coincidence, you can do both of those by adding potassium carbonate (K2CO3).


In a traditional honey mead — a mead with no fruit or ingredients other than honey — potassium levels can vary wildly. Levels of 30–2,500 ppm potassium ions (K+) have been reported in various types of honey, with lighter colored honeys generally having lower levels (around 200 ppm). Once diluted with water, this range would drop significantly, depending on much water is added (at a minimum, around a three-fold dilution). However, in order to support a healthy fermentation, a mead must should have at least 300 ppm potassium.



In a traditional honey mead, as in beer or wine, the pH drops during fermentation. The pH of the initial honey and water mixture may fall into a wide range (3.5–5.0), depending on the acids in the honey and the level of carbonates in your water. However, the honey and water mixture is poorly buffered, and its fermentation can quickly drop the pH to a level below which the yeast are inhibited. (Below a pH of 3.2, most wine yeasts start to struggle.) A starting pH of 3.6–3.9 will allow the mead to ferment and reach a final pH of 3.0–3.2, and occasionally as low as 2.9. If the mead starts at 3.5 or below, it may ferment sluggishly or not at all. If you adjust the pH initially, you should not need to adjust it again during fermentation. (Note that some meadmakers start as low as 3.4, then adjust the pH if it gets too low during the fermentation.)


The Solution

Although you could supplement the must with potassium by adding any potassium salt and separately adjust the pH with calcium carbonate or sodium bicarbonate, you can “kill two birds with one stone,” as Schramm puts it, by adding potassium carbonate (K2CO3).

How much potassium carbonate to add should depend on your initial potassium levels. Unfortunately, there is no simple way to measure potassium levels in your mead must at home. However, because parts per million is roughly equal to milligrams per L, you can easily calculate how much K2CO3 you would need to add to 5 gallons (19 L) to reach 300 ppm if your mead must had 0 ppm initially — 19.0 L * 300 mg/L * 138 (FW K2CO3) /39.0 (FW 2 K) = 10,100 mg or 10.1 g (or 0.36 oz). You could also use 14.6 g (0.51 oz.) of potassium bicarbonate (KHCO3 : IUPAC name potassium hydrogen carbonate) to 5 gallons (19 L) of must to yield the same thing.

If you have a pH meter, you should measure the pH of your must initially. If it is below 3.6, add a small amount (around a gram or two) of K2CO3, stir and keep adding small amounts until the pH climbs to this level.

So how much K2COshould you add, given that your potassium levels are unknown and the pH of your must may be over 3.6 naturally? Your first move should be to adjust your pH, if needed. If, in doing this, you add 300 ppm K+ or more to the must, then that’s all you need. If not, keep adding potassium carbonate until you have added a total of 10 grams (0.36 oz.) of K2CO3 to your must. This will result in 300 ppm of potassium ions added to whatever unknown (but likely small) amount of potassium in the must.


Ken Schramm is set to open Schramm’s Mead in a matter of weeks. His meadery will initially offer some melomels, and later some traditional meads (as they take longer to ferment). Most of his meads will be made with local Michigan honey and he is looking into becoming a beekeeper.


  1. Guilherme Silva says

    So, if I understood correctly, the solution is to always add the 10g of potassium carbonate, and the pH adjustment happens anyway by doing this.
    Can there be any issue if the pH is higher than recommended? Or that amount of potassium carbonate is not enough to have a big impact?

    • Chris Colby says

      I recommend adjusting your pH first, then adding more potassium carbonate if needed to fix the (probable) potassium deficiency. However, you could also approach it the other way, add 10 g per 5 gallons and then test your pH to see if you need more. The point is you need to satisfy both requirements. The order isn’t important.

      I suppose it is (at least theoretically) possible that, in some cases, adding enough potassium carbonate to raise the potassium levels would result in a pH above 3.9 (the top of Schramm’s target pH zone). But, I’m not sure this would harm anything. Post-boil wort pH is almost always higher than this (4.0–4.2).

  2. Christian says

    I’d like to try this but I cannot find potassium carbonate from a homebrew or food supplier. They only sell potassium bicarbonate. Is there a big difference or will it achieve the same result?

    • Mike O'Brien says

      From the article:
      You could also use 14.6 g (0.51 oz.) of potassium bicarbonate (KHCO3 : IUPAC name potassium hydrogen carbonate) to 5 gallons (19 L) of must to yield the same thing.

  3. Mike,
    Several questions:
    1) What do you do if the pH is high (and what is too high)? How do you bring it down?

    More specifically, I am experimenting with 2 new meads and have two going, both are at pH = 4.6.
    The first uses Fleishman’s yeast and SG=1.012, pH = 4.6 before I added the oranges.

    The second is a combination of honey and maple syrup, again with a pH = 4.6

    Your article mentioned an optimal pH between 3.6 to 3.9 (as does Schramm) although page 56 references a study that shows 3.7 to 4.6.

    Nonetheless, I think I should bring the pH down. I pitched the yeast 2 weeks ago is much of the primary fermentation is over. The Ancient Orange pH as of today (with oranges added) is 3.4.

    What should I do (or what should I have done in the beginning to have brought down the pH levels down?

    2) Is there a target pH range for post-fermentation? That is, if the pH is too low, should you try to increase it to improve the mead?

    3) If a sweet mead is a little sappy, does adding calcium carbonate remove the sappiness?

    Many, many thanks in advance.

    – James

  4. akshay patole says

    i have not potassium carbonate then what i do.

  5. Regina Gale says

    My husband makes delicious mead. I am on a restricted diet and must watch my potassium. I have a Cronic kidney disease . Could anybody tell me how much potassium is in a glass (4oz.) of mead?

    • HÃ¥ller med om att det är en trygghet att ha en buffert pÃ¥ kontot. Sover själv mycket bättre nu när jag har en mÃ¥nadslön pÃ¥ spr.oontktaFast allra helst ska man väl ha tre till sex mÃ¥nadslöner pÃ¥ ett sparkonto säger experterna.

  6. Hello
    In calculating the amount of K2CO3 to add to obtain 300 ppm of K2. Yo,u give in the formula, K2 = FW 39. But since there are two potassium atoms, it would not be 2×39 = 78?
    19.0 L * 300 mg/L * [78.0 (FW 2 K) / 138 (FW K2CO3)] = 3221 mg = 3.2g

  7. Oliver — I think the two K atoms are incorporated in the original calculation. I get the same result.

    FWIW, I add K in 25% increments over Days 1-4. By my calculations, the full 300 ppm can be achieved by adding K2CO3 at 2 g/gal, KHCO3 at 2.9 g/gal, K2HPO4 at 2.5 g/gal, OR KH2PO4 at 4 g/gal. And you can mix and match. As I understand it, the carbonate compounds tend to raise pH, whereas the phosphate compounds tend to lower it (but how much maybe depends on the presence of calcium ions). So at each step you can pick the compound that moves you in the desired direction. This adjustment should be cautious, keeping in mind that the yeast will produce organic acids that gradually lower the pH as the ferment proceeds.

  8. Janne Goman says

    Hey mead makers,

    I have a mead test going on in which I divided my 24 brix /14 abv mead must into 12 bottles. I experimented also with K2CO3. I’m starting to think that K2CO3 is not actually providing any potassium as ions (K+ form) for the yeast.
    As you add, in theory, K2CO3 dissolves into the must and provides 2x K+ and 1x CO3-2 atoms. After this, K+ instantly reacts with water and forms KOH, potassium hydroxide. This strong base will raise the pH. I noticed while making my musts for the experiment, that initial pH of 3,7 rose up to 7,1 after I used the same calculation of K2CO3 as mentioned above. It seems that the pH will raise due to KOH, not the free carbonate.
    Also, is the potassium anymore available to be used by the yeast since it has formed a KOH and its not anymore as ionic state?
    In the study called “Imbalance of pH and Potassium Concentration as a Cause of Stuck Fermentations” where they tested potassiums effects on completing the fermentation, they used potassium chloride KCl and potassium sulphate K2SO4.
    It would be interesting to try different potassium salts and their effects on pH.
    I quess the yeast can use the potassium even if its not in its ionic state.

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