I'm brewing a German Pils and going for a crisp hoppy finish, so I am trying to match the "Yellow Dry" profile in Beersmith, Ca 50, Mg 10, Na 5, SO4 105, Cl 45, HCO3 0.
However, my home water is pretty far off from this: Ca 35, Mg 9 Na 69, SO4 22, Cl 83, HCO3 91.
With salt additions of gypsum and epsom salt I can get closer: Ca 55, Mg 17, Na 69, SO4 103, Cl 83, HCO3 91
This gives me a sulfate/chloride ratio of 1.2 as opposed to the 2.3 of the target
Obviously, I will never get down to zero bicarbonate unless I replace my water with distilled. My question is will there be a perceptible difference between an S/C ratio of 1.2 vs 2.3? Is it worth me shlepping to store and spending the money on distilled water?
My opinion is that 91 ppm bicarbonate has the potential to just tip the balance on a good liquor profile, but the outcome wouldn't be a disaster.
Your potential profile has 55 ppm calcium with 91 ppm HCO3 which, put in equivalent terms, has in one litre ( any influence of magnesium is ignored) 2.75 mEq from calcium and 1.49 mEq from alkalinity. Now alkalinity will raise pH three and a half times as much calcium will lower it, meaning its alkalinity has almost double the power to raise pH than calcium's ability to lower it. Therefore, whatever mash pH your grains would produce in purely distilled water, mash pH would be higher in the proposed profile.
Judicious use of acid will neutralize alkalinity and potentially negate the reason to use distilled water. Here in UK we will frequently use hydrochloric acid to reduce alkalinity and at the same time increasing chloride ions, or similarly use sulfuric acid and increase sulfate ions. By combining both acids, the sulfate/chloride ratio can also be varied. As already advised by
@Silver_Is_Money, lactic and other acids are readily available and more commonly used outside of UK, but reducing alkalinity with any acid will reduce that liquor's ability to raise pH.
The data is for grains I currently use, but shouldn't be vastly different to many other malts.
100% of this malt mashed in distilled water should produce pH between 5.9 and 6.1 as in the link, but higher using your profile with 91 ppm HCO3. Reducing HCO3 by half, would balance the pH lowering power of calcium, so when mash pH should be similar to that in distilled water. If alkalinity was further reduce, mash pH should be lower than with distilled water.
I would not advise mashing a Pils between pH 5.8 and 5.9 and I doubt Rochefort do. The two are very different beers of course, with Rochefort the more forgiving, but Stan Hieronymus's book contains several statements different to other accounts in which I have more confidence.
By including a proportion of
this malt would reduce pH, although it might not be desirable, but with its lower natural mash pH, it is something to consider.