I am pretty sure that my estimation of the Biocarbonates (HCO3 or CaCO3) has got to be off. But I still want to double-check with the community and see if my math is at least on.
Got your math nerd hat on?
So I'm delving deeper into the math and science behind brewing — much in part to the book "Designing Great Beers" by Ray Daniels — and I'm presently wrapping my head around water chemistry (or trying to anyway) but ran into a red flag when I was evaluating just how much Calcium I would need to bring the levels down to earth. It seemed pretty extreme, so I thought I would confer with the chemistry and math geeks here and make sure my calculations were correct, and if they are, how I can bring the pH level down without introducing off flavors like chlorine, salt, etc.Water profile
For starters, I checked with my city water source and they were able to provide the general pH range (7.5-8.1), the Calcium reading (170 ppm), and Magnesium reading (28 ppm), but did not have any readings for Biocarbonates. So based upon the formula that Daniels provided:
pH = (0.028 x [(Biocarbonate ppm x 0.056) - (Calcium ppm x 0.04) - (Magnesium ppm x 0.033)] )
I guestimated (based upon reverse-engineering the formula) that our Biocarbonate reading must be in the ballpark of 4921 ppm, so the end formula would have these values:
7.5pH = (0.028 x [(4921 ppm x 0.056) - (170 ppm x 0.04) - (28 ppm x 0.033)])Achieving 5.5 pH
So I took the same formula, but factored in 5.5 as the pH rating, kept the Biocarbonates and the Magnesium at the same value (assuming that those two would remain constant), and then figured out how much Calcium it would take to bring the pH level down to 5.5. That formula is:
5.5pH = (0.028 x [(4921 ppm Biocarbonates x 0.056) - (1956 ppm Calcium x 0.04) - (28 ppm Magnesium x 0.033)] )
And the difference of ppm of Calcium between a pH level of 7.5 and 5.5 comes out to be about 1786 ppm of Calcium — and because Calcium is only 27% of Calcium Chloride, it would take 6615 ppm of Calcium Chloride to reduce the pH to 5.5. And if I have my percentages right, that would also mean adding over 3100 ppm of Chloride.
Translate that into ten gallons of strike and sparge water as an example, that would be nearly nine
ounces of Calcium Chloride to bring the pH down.
If I'm not mistaken (and I probably am — I am a man, a home brewer, and am prone to err), that much Calcium Chloride could have a pretty bad effect on the flavor of the water, the mash and in turn, the beer.
Do my figures look correct in terms of the correction of pH levels? Or is it possible that my Biocarbonates guestimation is off altogether and is by far too high? Since the city doesn't measure CaCO3, I'm stuck trying to guestimate that without sending my water in for a professional reading.
I've no real interest in answers like "just go get some distilled water" — simply put, I don't learn anything from copping out and grabbing distilled water off the shelf. Part of this exercise is to learn some facets of the chemistry of water and how I can correct it as a home brewer (within reason).
And just to be clear, my beers don't taste bad at all — I can't say that having a higher mash pH (of about 6.3 or so, which is what I've been averaging) has had a dramatic effect on my beer. But I am trying to really dial it down and improve my mastery of water chemistry.
Thanks in advance.