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

Advertisement