This is an attempt to calculate water adjustments for a 3-gallon batch of a rye IPA. (No sparge.) I used the pale ale profile in Bru’n Water but took advice to keep sulfates below 150 ppm. For 6 gallons of RO mash water, I come up with 6 grams of gypsum, 1.5 grams of calcium chloride, and 6 ml of 25% phosphoric acid. Does this look right?
Bru’n Water v.4.0 Water Adjustments
Denny’s Wry Smile Half Batch
Profiles (ppm) Exist Mash Finished
Ca 0 81 81
Mg 0 0 0
Na 0 8 8
SO4 0 148 148
Cl 0 36 36
HCO3 0 -32 NA
SO4/Cl Ratio 4.1
Batch Volume 3.0 Gallons
Total Mash 6.0 Gallons
Mash Dilution 6.0 Gallons
Total Sparge 0.0 Gallons
Sparge Dilution 0.0 Gallons
Estimated Mash pH 5.32 SU
Mineral Additions (gm) Mash Sparge
Gypsum 6.0 0.0
Calcium Chloride 1.5 0.0
Epsom Salt 0.0 0.0
Mag Chloride 0.0 0.0
Canning Salt 0.0 0.0
Baking Soda 0.0 Not Recommended
Chalk 0.0 Not Recommended
Pickling Lime 0.0 Not Recommended
Looks fine. Somewhere between 5.3 and 5.4 should be good. While I prefer the high sulfate of the pale ale profile, its safer to start low and see where your preference lays. The good thing with gypsum, is that you can still dose your beer after fermentation.
I suggest you figure out how much gypsum it would take to bring the sulfate content of a glass of your finished beer from your 150 ppm target to the 300 ppm range. Its going to be a teeny amount. Then add to a glass of beer and mix in. It should dissolve in a minute or so. Taste the stock and gypsumed beers and see which you prefer. Do be careful to keep the carbonation and temperature similar for both samples. The higher gypsum dose should make the beer finish drier. That may be a desirable or undesirable effect, depending on the style, the bittering level, and your tastes. Adding post-fermentation gypsum is especially useful when you’ve created a beer that seems too full or sweet.
You don’t have to accept where the beer finished up, if its too full or sweet.