I have not had to add acidulated malt to reach the pH window I target (5.3 +/- .1). However, I take specific steps to ensure that’s the case. Some other brewer using different variables may need to use acid malt.
TL;DR — Once I understood my water profile and water treatments, I quit worrying about mash pH at all. No PITA spreadsheet reinventing the wheel days before brewing or tedious salt measurements on gram scales.
Here’s what I do:
[1] Adjust brewing liquor: de-aerate RO or distilled water with 1 gram per gallon each active dry yeast and sugar heated to 114°F for at least 20 min. After at least 20 min but up to two days, continue to heat to strike temp. (Ref:
https://www.themodernbrewhouse.com/deoxygenation-revisited/). Add 1/2 tsp hydrated Brewtan B to strike liquor at strike temp prior to mash in. (Ref: J. Formanek)
[2] Mash pH control: ONLY mash malts/grains that require it. DO NOT mash malts that don’t require it. (Dark Crystal and Roast malts.) They screw with pH. Hold Dark Crystal and Roast malts to Mash Out for a 30 min hot steep. Most dark grains are simply added for flavor and color, so I don’t let them ruin my mash chemistry and drive unwanted salt additions. (Ref: G Strong)
[3] Adjust Mash: use 50-100 ppm Ca as a co-factor for the amylase enzymes and to help protect α-amylase at normal mashing temperatures. Calcium in the water reacts with phosphates in the grain husks to release phytic acid, which lowers the mash pH naturally. (Ref: G Strong) Also add 1 tsp (~3-4 grams) Ascorbic Acid as a stabilizer. Add adjustments direct to grain prior to adding to MLT prior adding brewhaus liquor.
[4] To get Ca, use 1 tsp calcium chloride to each 5 gallons of water treated. For soft water beers (i.e Pils, Helles) use half the baseline amount of calcium chloride. For British beers: Add gypsum as well as calcium chloride. For very minerally beers (Export, Burton ale): Double the calcium chloride and the gypsum. (Ref: AJ DeLange) I do this in the BeerSmith water module to validate water volume, Ca ppm, and sulfate:chloride ratio for British beers: 2:1 for bitter beers, 1:2 for milds, and 1:3 for stouts and porters. (Ref: G Strong)
*Disclaimer*: Any comment I add is simply the way I brew beer. I am not paid or sponsored by anyone. There are certainly other ways that can be equally effective which other brewers may contribute. This is what I’ve found that works for me using my equipment and processes so I offer this for your consideration. YMMV