There are a lot of ways to adjust for pH. I’d say most use some sort of prediction tool to guess what the full grain bill pH will be and make an acid adjustment based on the recommendation. Usually lactic or phosphoric acid is used.
Careful which pH adjustment you use in BeerSmith. There are two choices. I’ve had the most luck with Martin’s Bru’nWater which is one of the choices. Other tools give different recommendations based on their differing calculations.
Others may add acid malt at 2-3% of the grain bill vs the lactic or phosphoric acid. AJ DeLange’s water adjustment advice uses this method.
Another way to account for mash pH is to use a method Gordon Strong advocates. That is withhold all the dark grains until mash out/vorlauf. By then the mash is complete and the dark grains have least affect on the outcome. I use full volume no sparge with this method.
I like to use 50-100 ppm Ca as a co-factor for the amylase enzymes and to help protect α-amylase at normal mashing temperatures. Ca in the water reacts with phosphates in the grain husks to release phytic acid, which lowers the mash pH naturally. (Ref: G Strong) Because the recommendation is ppm, the amount changes with water volume. So full volume no sparge, or less volume with sparge is accounted for.
Though G Strong recommends treating water with phosphoric acid to adjust to 5.2 before strike or sparge, I add 1 tsp (~3-4 grams) Ascorbic Acid, a proven antioxidant, though slightly less effective in solution at scavenging oxygen than NaMeta. However, enzymes exist within the malt that increase the effectiveness of AA as an oxygen scavenger. (Ref:
http://www.germanbrewing.net/docs/On_Brewing_Bavarian_Helles_v3.pdf) More importantly, it’s a weak acid that assists Ca to get mash pH in the desired range.
*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