[narcout]

These are some pH measurements I took while brewing a Munich Dunkel last night, in case anyone finds them interesting.  The grain bill was 10.5 lbs. Munich (Best Malz) and 6 oz. of Dehusked Carafa II (added during the sparge).

Mash (3.4 gallons of distilled with mineral additions) - 5.37 (Bru'n Water predicted 5.4)
Infusion (2 gallons of distilled) - 5.48
Batch Sparge (3.1 gallons of distilled) - 5.55
Pre-boil - 5.49
Post-boil - 5.44

I was surprised by the rise in pH during the sparge since I added the Carafa at that time.

The pH did not change the last time I took pre and post boil measurements, so that was also something I did not expect.

I'm using an MW101, but there is definitely some variability in my accuracy.  Samples were at 72 degrees F.

[PORTERHAUS]

Everything looks pretty good. I guess a little lower pre and post boil ph wouldn't hurt but seems to be in range. I also do not see a drop in boil ph at times, it seems to be random. but I have noticed that as well..or sometimes its only a very small drop.

[mchrispen]

It makes sense that the infusion of distilled diluted the acidity of the mash and it raised the pH a bit. Distilled is technically neutral, but your water:grist ratio changed... so the thinner mash buffered the available acidity. Assuming you didn't add any additional acid in the process.

[narcout]

I guess a little lower pre and post boil ph wouldn't hurt but seems to be in range.

I've been experimenting with using 10% phosphoric acid to lower the pre-boil pH, trying to get a feel for how much it takes to hit a given target.  I need to do some more research on what exactly that target should be.

It makes sense that the infusion of distilled diluted the acidity of the mash and it raised the pH a bit.

I was expecting the rise from the first infusion (which I could easily control with a little acid), but I was surprised by the rise during the sparge because I thought the addition of the carafa would counteract it (though it's not why I added it then).

[mchrispen]

Even powdered, it takes time for those malts to completely hydrate and the acid distribute through the mash completely. If I recall, the acidity from a small dose of black malt isn't all that significant, unless you are really dropping pounds of it.