Water Profile for Oatmeal Stout

Figured I should make sure I have a decent handle on my mineral addition before I get to brew day. I am starting with distilled water and my grain bill is as follows:

9 lbs Maris Otter (67.3%)
1 lb 6 oz Rolled Oats (toasted) (10.3%)
1 lb 2 oz chocolate malt (8.4%)
12 oz Crystal 120L (5.6%)
9 oz English Roasted Barley (4.2%)
9 oz Victory Malt (4.2%)

and my target water profile is:

Ca:56.2
Mg:5.2
Na:20.8
SO4:35.3
Cl:49.9
BiCarbonate:121.7

Which gives me an estimated mash Ph of 5.3. Do I have too much or too little of anything?

It's hard to say. You do have quite a bit of colored malts but where they take you depends on the particular malts. This is really a case where only a pH meter will tell you where you actually are but I'm guessing you are probably OK. There is no need for the Mg but if you are using it as a way to get a bit more sulfate in there that's fine.

Seems to be a reasonable water target. The bicarbonate content is modest and the resulting pH prediction is on the low side for a stout that might be intended to be fuller and rounder. I find that a slightly higher mash pH of 5.5 in those darker styles can produce a better beer.

If you were brewing a dry stout, that low mash pH could actually be beneficial for flavor and perception. Tailoring your mash and kettle wort pH to the style can be beneficial in some cases. For the most part, a kettle wort falling in the 5.3 to 5.5 range will be safe.

The final question is: how are you adding that bicarbonate? Hopefully you are planning on employing lime or baking soda since chalk does not work in the mashing timeframe.

I was actually going to use pickling lime to help get my calcium up over the recommended 50ppm. I was then going to use baking soda to adjust during mash if the ph was too low. After reading about chalk I haven't used it at all.

I was aiming for 5.2 since my last brew the PH was about .4 over the predicted PH. I figure if I shoot for 5.2 I have a better chance of hitting between 5.2 and 5.5 and if not will have some Acid malt crushed on hand and baking soda ready to go.

brewmeister13 said:

Figured I should make sure I have a decent handle on my mineral addition before I get to brew day. I am starting with distilled water and my grain bill is as follows:

9 lbs Maris Otter (67.3%)
1 lb 6 oz Rolled Oats (toasted) (10.3%)
1 lb 2 oz chocolate malt (8.4%)
12 oz Crystal 120L (5.6%)
9 oz English Roasted Barley (4.2%)
9 oz Victory Malt (4.2%)

and my target water profile is:

Ca:56.2
Mg:5.2
Na:20.8
SO4:35.3
Cl:49.9
BiCarbonate:121.7

Which gives me an estimated mash Ph of 5.3. Do I have too much or too little of anything?

Click to expand...

This looks very similar to Jamil's Brewing Classic Styles Oatmeal Stout. I've got some data from brewing that beer that might be helpful:

1.46 qt/lb Mash Ratio
Mash water effective alkalinity = 88 ppm (mixture or my tap water with RO)
Sparge water alkalinity = 0 ppm (RO)
All water treated with 0.5 gram/gallon CaCl2
Final water profile (mash + sparge):
Ca = 48 ppm
Mg = 6 ppm
Na = 2 ppm
Cl = 70 ppm
SO4 = 3 ppm
NOTE: Mg, Na, SO4 from blended tap water (Wards lab report) not significant levels here

Mash pH at 15 minutes = 5.40 (room temperature, freshly 2-point calibrated pH meter), no acid added to mash or (batch) sparge