Because it is typically the largest component of your grist, the acidity of the base malt usually has the greatest effect on the resulting mashing pH. Some base malts can have a lower than typical distilled water pH. A typical 2L to 3L base malt often has a distilled water pH in the 5.7 to 5.8 range. However, some maltsters can either purposely or mistakenly have batches of base malt that is more acidic. In the case of that Boh Pils malt, Weyermann confirmed that they made a mistake and contaminated a batch with acid malt. That 5.2 pH is NOT typical.