Water Treatment for Brewing 3.5: Solubility Limits

[Miniseries Part One, Two, Three, Three-point-Five, Three-point-Six, Four]

Bonus post!  I’ve never liked the idea of using volumetric approximations for adding brewing salts, and most scales aren’t good enough to measure a few grams at a time (accurately that is- most will still pretend to try).  One way around that is to dissolve the salt in water in a high concentration, then measure a precise volume of solution to add to the brewing water, either by weight or volume.  Of course that only works if the water can hold enough of the salt in question to make it worth your while- enter: solubility limits.

In the tables below, solubility limits of different salts are listed at various temperatures, including refrigerator, in case you want to save some solution, room temperature for mixing, and strike and boiling, as some salts exhibit retrograde solubility (they are less soluble as the temperature goes up).  The values listed in the first table are in grams per gallon, and grams per liter in the second.  Just like sugar in sweet tea, you can only add so much before it just sits on the bottom and doesn’t dissolve into the water.

There are two quick conclusions I draw from the data below:

  1. The number of salts it would be useful to try the above measuring scheme with are limited.  It would likely work only with calcium chloride, sodium chloride, the magnesium compounds, and perhaps sodium carbonate.  Of these, only calcium chloride is useful to me, and even it sees limited use- my water is already fairly high in chloride ions.
  2. The use of calcium carbonate in water treatment for brewing is extremely limited.  Given its retrograde solubility, strike is probably the limiting temperature.  Once it is in the mash, it will at least partially react with grain compounds, so it should not precipitate in the boil.  Once I added near the maximum amount of this salt to the room temperature water, only to bring it to strike temperature and have much of it coat my brew pot.  Its likely that if added to the mash directly instead of the strike water you could add more, but I can’t speak to the exact amounts- you should be able to dissolve more at lower pH levels.  [2013.11.12 UPDATE: I ran across a really neat trick via the Brau Kaiser on how to dissolve additional calcium carbonate into carbonated water.]
 Values in grams per gallon fridge room strike boil
calcium carbonate (calcite) chalk 0.246 0.2347 0.132 0.076
calcium chloride 2252.1 2819.8 5469 6018
calcium hydroxide slaking lime 7.1537 6.5481 3.596 2.46
calcium sulfate gypsum 8.4406 9.6518 8.952 7.759
magnesium chloride 2002.3 2066.6 2454 2774
magnesium sulfate 832.7 1275.5 2101 1908
sodium carbonate baking soda 264.95 813.78 1681 1722
sodium chloride table salt 1349.4 1358.4 1427 1476
 Values in grams per liter fridge room strike boil
calcium carbonate (calcite) chalk 0.065 0.062 0.035 0.02
calcium chloride 595 745 1445 1590
calcium hydroxide slaking lime 1.89 1.73 0.95 0.65
calcium sulfate gypsum 2.23 2.55 2.365 2.05
magnesium chloride 529 546 648.3 733
magnesium sulfate 220 337 555 504
sodium carbonate baking soda 70 215 444.3 455
sodium chloride table salt 356.5 358.9 377 389.9

Read on in part 3.6 for some weight to volume conversions to measure the salts by teaspoon or milliliter.

All data from en.wikipedia.org/wiki/Solubility_table except calcium carbonate from Mixed salt crystallisation fouling, Helalizadeha, Müller-Steinhagena, and Jamialahmadib; water volumes measured at standard temperature and pressure (all data originally in grams solute per 100 grams water).  Some data linearly extrapolated from that given.

[Miniseries Part One, Two, Three, Three-point-Five, Three-point-Six, Four]

– Dennis,
Life, Fermented


About Dennis
Home brewer, home chef, garage tinkerer. Author of Life Fermented blog.

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