Today was my 3rd all grain brew and I have some questions regarding mash pH, pre-boil pH, and post-boil pH.
I brewed an oatmeal stout (the one in Brewing Classic Styles) so my grain bill looked like this:
9.4 lbs british pale ale malt
1 lbs oats (toasted in the oven)
12 oz chocolate malt
12 oz victory malt
8 oz black barley
8 oz crystal 80
I used the Bru’n Water spreadsheet to calculate my water additions, using Black Balanced as my target.
I diluted my filtered tap water with 50% distilled which gave me a starting water profile like this:
Calcium 39.0
Magnesium 17.0
Sodium 19.0
Sulfate 82.5
Chloride 38.5
Bicarbonate 67.0
Cations 4.2
Anions 3.9
Total Hardness 167
Alkalinity 55
RA 18
SO4/Cl ratio 2.1
My mash water volume was 3.7 gallons. I added 0.4g baking soda and 1.5g pickling lime to arrive at this:
Calcium 96.1
Magnesium 17.0
Sodium 26.2
Sulfate 82.5
Chloride 38.5
Bicarbonate 260.1
Cations 7.3
Anions 7.1
Total Hardness 310
Alkalinity 215
RA 137
SO4/Cl ratio 2.1
Additionally, I added 3g gypsum, 1.6g calcium chloride, 2.9ml lactic acid to the sparge water, per the spreadsheet.
The estimated room temperature mash pH was 5.3.
After 15 minutes of mashing, I stirred the mash then took a sample from the top.
pH at 15 minutes was 5.8 at 70F
pH of 1st runnings was 5.5 at 70F
pH of pre-boil wort was 5.5 at 70F
pH of post-boil wort was 6.5 at 70F <— ???
Do these pH numbers look appropriate? I checked my meter prior to brewing with 4 & 7 calibration liquid and
it was fine.
If I remove all of the darker grains from the spreadsheet the estimated pH shoots up to 6.4. Is it possible that the spreadsheet is overestimating the dark malt’s pH lowering magic (yes, it’s magic, at least until I understand it!