So, brewing a Hefeweizen yesterday.13 gallons of RO water for the mash.
Per BS3,
Salt additions: 5.67g CaCl2
4.47g MgSO4
2.71g CaSO4
2.41g NaHCO3
4ml Lactic Acid 88%
I also added 2lbs of Acid Malt
21lbs 3.6 oz Wheat Malt
12lbs 12.1 oz Pilsner
12.6 oz Melanoiden
1lb Rice Hulls
I mashed for 15 mins, pulled and cooled a sample to 65*, tested pH and my recently calibrated pH meter gave me a reading of 5.12 Much lower than my estimated 5.25
I proceeded with the remainder of a 60 min mash, took another sample cooled to 65* and this time I got a reading of 5.32 I took a 3rd sample and got the same result.
I rarely miss my pH estimates but in doing so, I felt taking a second and third sample at the end of the mash made good sense.
So, my question is why, and can, the pH change that much?
That pH response is common. I’ve conducted over 50 test mashes and the consistent response is that initial pH is extremely likely to be quite low and it will rise by several tenths during the mashing period. I find that mash pH tends to stabilize around the 45 minute mark.
LESSON: If your early mash pH measurement says that it is below your targeted pH, you’re in good shape. It will rise.
I’ve often seen you report this phenomenon, and I certainly don’t doubt you. But I’ve always found (over easily as many batches) that my pH locks in very quickly, holds steady through the mash, and is in fact the same as the wort pH at the start of the boil. What could explain this? Is there something we might be doing differently – in our establishing the conditions in the mash – that could account for the stability I observe, vs the drift you observe? I’m sure we’ve had an exchange about this in the past here on the forum when I’ve contended – counter to your contention – that it’s futile to attempt to correct pH after mashing in, but never addressing possible explanations.
To the OP: If Martin says you’re good, buy it. I may have consistent experience, but he has the knowledge of the mechanisms at work. That’s why I’m asking him this question, and not in any way suggesting that there might be anything fishy about your observations.
That is not the recommendation. The recommendation is for the use of 1% by grist weight of acid malt for every 0.1 pH points you wish to lower the mash pH.
The amount of Acid Malt was determined by BS3. I have been relying on BS3 for my water adjustments ever since i started to adjust my water profiles and to my knowledge and experiences with it, I hit my numbers consistently.