Imperial Stout Water Sanity Check

[rippajak]

I am in the midst of brewing up a few big beers to set back and age for winter, and the next I have on deck is an imperial stout. The 26.75 lb grain bill I have planned necessitates a fairly thick mash (1.0 qt/lb) in order to reserve enough water for a decent fly-sparge. My tap water is fairly low in mineral content, and I have been trying to balance that relatively small volume of low alkalinity water against a large amount of dark roasted grain using Bru'n Water.
The problem that I'm running into is that it seems to take a LOT of alkalinity additions to balance out to a desirable pH. In particular, I would be adding enough pickling lime to get the calcium content close to 100 ppm. Although Bru'n Water doesn't seem to note any taste threshold for calcium, this seems to be pushing the envelope a bit.
I am posting below the text readout of the profile I have cobbled together. I am hoping that some people more experienced than I in the field of water treatment will weigh in. Are these additions going to result in something undrinkable? Would I be better off to go with a higher water-to-grist ratio and just accept a lower sparge volume? Any thoughts are well appreciated.

Profiles (ppm) Existing Mash Finished
Ca-------------13------99----91
Mg-------------4-------4-----4
Na-------------16------70----50
SO4------------33------33---33
Cl--------------7-------7-----49
HCO3----------43------448---NA
SO4/Cl Ratio: 0.7

Batch Volume: 5.5 Gallons
Total Mash: 6.7 Gallons
Total Sparge: 4.0 Gallons
Estimated Mash pH: 5.30

Mineral Additions (gm) Mash Boil
Calcium Chloride-------0.0-----2.7
Baking Soda-----------5.0
Pickling Lime-----------4.0

 

[mabrungard]

Bloomington water is an anachronism with respect to typical Indiana water...it has very modest alkalinity. Therefore, its not ideal for brewing many stouts and porters (great for pale beers though). I was actually brought in to help correct this same problem for Bad Elmer several years ago.

In an ale, don't worry too much about having a lot of calcium in the water. It doesn't adversely affect the flavor. It appears that your approach should be fine. Your mash pH is still a bit lower than I find produces smooth roast flavor, but at least its not lower. Bringing it up another tenth or two is my preference.

 

[rippajak]

Thanks for weighing in, Martin. It eases my mind to have the advice of a true water guru.

If I were to try and bring the pH up a bit more, would you recommend using more baking soda, more lime, or a combination of both? I feel like having a bit more sodium content might accentuate the malt flavors I'm shooting for, but I also don't want to accidentally stumble into "briny" territory.

 

[mabrungard]

The amount of baking soda needed to boost mash pH for our brews is not large enough to create salty flavor in beer. I find that the typical net sodium increase when using baking soda is less than 50 ppm in the kettle. That isn't enough to create salty perception.

PS: Don't forget that baking soda is not added to the sparging water, so sparging will dilute your mashing wort's total sodium content. The supporter's version of Bru'n Water does perform the dilution calculation for you, so that you'll see what your sodium content actually is in the kettle.

 

[ajdelange]

The problem that I'm running into is that it seems to take a LOT of alkalinity additions to balance out to a desirable pH.

The amount of alkalinity required depends on the acidity (DI mash pH and buffering) and amount of the roasted (an other high colored, if any) grains used relative to the amount of base malt and its alkalinity (DI mash pH and buffering). Your source water does not have much alkalinity (about 2/3 of a mEq/L). Even with that little you could probably support 10 - 15% roast barley without going too low in mash pH.

But you don't want to be relying on my 'probably' or some brewing program if you are making special big beers in the hopes they will satisfy you through the long winter to come. So use a program or programs to come up with estimates and then check with a test mashes using the estimates.