Late mash pH adjustment effects?

Brewing Processes
1

Got my mash rolling for my altbier this morning and according to Brunwater I was targeting a 5.4 mash pH with my salt adjustments and RO water.  I took a mash pH reading about 5-10 minutes into the mash with my just calibrated MW101 meter and was getting a 5.18-5.2 pH.  I added some pickling lime to the mash and was able to bring it up to about 5.41.

Herein lies my question…my mash sat at the initial reading of 5.18-5.2 for about 30 minutes prior to adjusting it with pickling lime to a 5.4 where it then sat for the remainder of the mash (30 more minutes).

1.  What, if any, issues could arise from this late mash pH change?

2.  Since I seem to be having trouble “nailing” my last 4 brews with regards to mash pH, just how accurate do salt and water measurements have to be?  I use a postal scale for salts that measures to nearest .01 g (I may sometimes be off by .02-.03g at most with a measurement - does that really make a difference?).  And I measure my water fairly accurately (which I could probably look into a bit more closely).  Any suggestions?

2

Everything will be just fine.  It appears to me you are overthinking this.  If your pH is anywhere from like 5.1 to 5.5, everything will be great.

3

A late mash adjustment isn’t probably going to do much for you in terms of efficiency.  However, you will likely still impact your flavor profile a bit.

4

The FG came in at 1.051 (just shy of 1 gravity point) so I consider that a win.  The wort tasted great.  Still trying to get better at targeting my mash pH’s though.  Practice, practice, practice… = more beer!!  ;D