For a couple years now, I've been brewing using a partial mash method, with paying much attention to some of the finer points of what actually goes on in mashing. Only now, after re-reading some of my brewing lit. do I realize how important pH is, even for partial mashing, to get the most out of the bit of base malt that I does use.
I've also gotten into the habit of brewing using distilled water (read that somewhere too, I suppose). I'm gearing up to do a brown porter and was reading about acidity/tannins in the dark malts and just overall pH stuff for partial mashing. As long as I can keep the pH between 5.0 and 5.5 in the mash (looks like I'll probably have to have some calcium carbonate on hand), is using distilled water still a safe bet or should I be looking for something else (like spring water) to use in the mash?