I've been controlling the pH of my beers for about a year now...and I can tell you that they've been the best beers I've ever brewed. Started with ajdelange's brewing water primer and have kind of evolved from there.
In my experience so far, my goal for mash pH has been 5.2 at room temperature. As I said, the beers have been really good; I actually won Reserve Best of Show (with more than one of my entries winning first in their categories) in the county fair this past September. So, it's not just my own subjective opinion, ha.
But I recently read that pH is actually about .2 points higher at room temperature than at mash temperature, which means that pH 5.2 room temp is actually somewhere closer to 5.0 at mash temp. That's a little lower than the optimum range, which I'm sure is okay; as I said the beers have been really good, but what I want is to brew the very BEST that I can. So, I decided that I'd shoot for a room temp pH of 5.4-5.5 (mash pH of 5.2-5.3).
Yesterday, I brewed American IPA and measured the pH of my mash...it was right around 5.29 at room temperature. I wanted to increase this to about 5.5 and so I decided to add some baking soda. I had no idea how much to add and I couldn't find anything definitive online so I just added 1tsp to my mash. WOW...that literally took the pH up into the range of 6.5-6.7.
Thankfully, I had some acidulated malt measured and milled for just this occasion and I threw it in there and got the pH back down to around 5.43, which is good. Freaked me out though!
A couple of questions:
Generally speaking, is there a rule of thumb for using baking soda to do an ad hoc pH adjustment? I understand it depends on many many factors.
Speculation is probably the name of the game here, but is that brief (maybe 10 minutes or so) spike in pH gonna mess up the taste of my beer?? I'll find out for sure in about 4-5 weeks when I tap the keg, but if anyone has experience with this kind of situation, lemme know.