Gypsum vs calcium chloride: when to use which
They're the two workhorse brewing salts, and they solve the same problem (getting calcium into your water) while pulling the beer's balance in opposite directions. The choice isn't gypsum or calcium chloride; it's how much of each.
Same calcium, opposite anions
Calcium does quiet, unglamorous work: yeast flocculation, protein coagulation, oxalate removal, a small assist on mash pH. Either salt supplies it. What you're really choosing is the counter-ion. Sulfate (from gypsum, CaSO₄·2H₂O) accentuates hop character: bitterness finishes drier, quicker, more defined. Chloride (from CaCl₂) rounds the palate: malt reads fuller, sweeter, softer. Neither has much aroma or taste of its own at brewing levels; they work by changing how everything else is perceived.
When gypsum
Hop-forward beers: West Coast IPA, pale ale, anything where a crisp finish is the point. Classic targets run 150–300 ppm sulfate (Burton ran double that, which is more history lesson than target). If a hoppy beer tastes too sweet, gypsum is usually the fix.
When calcium chloride
Malt-forward and soft-finish beers: stouts, browns, European lagers, and most NEIPAs, where 100–150 ppm chloride against modest sulfate gives the pillowy fullness the style expects. If a malty beer tastes thin or sharp, chloride can help.
Almost always: both
Real profiles use both salts: the sulfate-to-chloride ratio sets the balance while total calcium stays in the 50–150 ppm range. The calculator's auto-suggest does exactly this arithmetic: chloride salt to the chloride target, gypsum to the sulfate target, epsom only if magnesium is genuinely short.
FAQ
How much does a gram actually add?
Per gram per gallon: gypsum adds 61.5 ppm calcium and 147.4 ppm sulfate; calcium chloride (dihydrate) adds 72 ppm calcium and 127.4 ppm chloride. Pure stoichiometry; every calculator worth using agrees on these.
Is there such a thing as too much?
Sulfate past roughly 350 ppm turns bitterness harsh and mineral for most palates; chloride past 150–200 ppm reads thick and salty-adjacent. Great beer lives well inside both limits.
My calcium chloride is a sticky clump. Is it still good?
It has absorbed water beyond the dihydrate form, so a gram delivers less than the numbers above. Either dissolve it into a solution of known strength or switch calculators to a liquid-CaCl₂ setting (brewwtr supports anhydrous, dihydrate, and liquid with a strength field).
Do they change mash pH?
Slightly, and in the same direction: the calcium reacts with malt phosphate and nudges pH down. It’s a secondary effect: dose these salts for flavor and yeast health, and control pH with acid.
Per-gram contributions are stoichiometric (verified from molecular weights in brewwtr's test suite). Flavor guidance follows Palmer & Kaminski, Water (2013), ch. 7, and common brewing practice.