how much acid are you typically adding to the mash?

[beltbuckle]

I have been acidifying my mash with hydrochloric acid the last several brews, and I am just wondering what a "typical" addition would be (either of HCl or lactic or whatever acid you use).


I brewed Jamil's Cal Common recipe, a 12 gallon batch, and the initial pH was 5.61. It took 10 mL (I use a 1mL pipette so the measurements should be pretty accurate) of 32% HCl to get the pH down to 5.41. pH is measured after cooling the sample down to 70-90 degrees and the pH meter does have ATC. I didn't go further than that since I am still getting a feel for how much is enough.

so is 1-2 mL per gallon of acid a fairly typical amount? I know it of course depends on the grist and the water, but just want to get a feel for the range.

[HopRunner]

I usually eat 1-2 tabs prior to brewing. I find putting it in the mash dilutes the effect too much.

[ajdelange]

so is 1-2 mL per gallon of acid a fairly typical amount? I know it of course depends on the grist and the water, but just want to get a feel for the range.

It seems a little high (for reference, 1 mL/gal would be enough to lower the pH of a gallon of water with alkalinity of 200 from pH 7 to pH 5.4) but if your water is alkaline and at a high pH and accounting for the buffering capacity of the grist it doesn't seem unreasonable. What counts is that the mash pH is where you want it to be. Just be sure to make certain the acid is uniformly mixed in and has had some time to react before you take the pH measurement.

[beltbuckle]

I used RO/DI water so for the mash so everything is pretty well known. I had 9 gallons with the following salts added (attempting to mimic san francisco water)

For 9 Gallon mash:
Gypsum - 1.1g
Epsom Salt - 0.2g
Table Salt - 1.5g
Chalk - 4.5g


which would yield something like this

Ca - 60
Mg - 0.6
Na - 17
Cl - 26
CO3 - 80

With an alkalinity of 66 and an estimated RA of 21.6. So that seems high to me as well. I did calibrate the pH meter with ph4 and 7 buffers so I am certain it was accurate. I also waited about 5 minutes from the acid additions to when I pulled a sample. I do a constant recirc during mash so everything should be mixing well. I wonder what the heck is going on.

[ajdelange]

The answer lies in the chalk addition. It would take 7.4 mL of acid to disssolve the 4.5 g of chalk and lower the pH of 9 gal. to 4.3. That's 2.67 mEq/L and as 4.3 defines alkalinity the alkalinity of 9 gal DI water to which you add 4.5 g of chalk is 133.5 (50 times 2.67). Note that the popular spreadsheets do not calculate alkalinity (or residual alkalnity) properly when carbonate is involved.

The amount of acid required to dissolve the chalk and get the pH to 5.4 is 6.9 mL. So leave the chalk out and the acid requirement should drop by approxumately 6.9 mL. The chalk adds 53 mg/L calcium and 89.5 mg/L chloride (by forcing you to add all that HCl). You'd get essentially the same result by adding 6.5 grams of CaCl.2H2O to the 9 gallons of RO water, have no residual bicarbonate and use less HCl to get to 5.4 (only what is required to overcome the buffering capacity of the malt).

Post the profile of the water you are trying to duplicate and I'll tell you what salts to add. The popular spreadsheets don't do synthesis very well either if carbonate is needed.

[brewinhard]

I usually eat 1-2 tabs prior to brewing. I find putting it in the mash dilutes the effect too much.

[siwelwerd]

Note that the popular spreadsheets do not calculate alkalinity (or residual alkalnity) properly when carbonate is involved.

[...]

The popular spreadsheets don't do synthesis very well either if carbonate is needed.

I think we need an unpopular spreadsheet to do these things well then!

[beltbuckle]

Post the profile of the water you are trying to duplicate and I'll tell you what salts to add. The popular spreadsheets don't do synthesis very well either if carbonate is needed.

Thanks for the explanation AJ. You're a great asset of this forum!

Here's the profile I was trying to get close to, it's the San Francisco water profile from BeerTools Pro.

Ca - 36
Mg - 25
Na - 17
HCO3 - 80
SO4 - 20
Cl - 26