It seems that if you no-sparge, this exaggerates the issue Martin is describing. More treated water equals more buffering capacity. Is this correct? Or does Bru'n Water account for this effect?
For example, my last mash was for a 4 srm hybrid. Using Bru'n Water, 2 ml of 88% Lactic acid in 8.25 gal. of water was needed to get the estimated mash pH to 5.4. As always, I took a sample at 15 minutes into the mash, cooled it, and it measured 4.8. The pH meter was calibrated earlier the same day. I assumed that the probe might be on its last legs, and just questioned the reading in my notes. But if it takes 45 minutes to reach its final pH, is there any value in measuring at 15 minutes?