update- brewed the czech pilsner today. i used distilled water and added my bru n water minerals for the profile. did not change my mill gap, or mash time, temp, or mash steps.
my efficiency went up about 7pts from previous mash of this recipe. the last time i did this recipe i used my well water, and made no adjustments to the water and the efficiency was 80% for the mash.
Today I maintained PH of 5.3 for mash and 5.5 on sparge. mash efficiency was 87%!