A.J. deLange has posted where for a period of time he routinely was of the habit of asking the (presumably small to mid-tier, but this being merely my speculation, as large scale could certainly be involved here as well) commercial brewers whom he was lecturing “How many of you take Mash pH readings?”, and he further stated that if he could summarize the general response he received it would be “You home brewers seem to be a lot more concerned about that than we are.”.
Achieving a knock-out pH of 5.1 after earlier having mashed at 4.7 pH would require the addition of a “basic” substance the likes of sodium hydroxide or potassium hydroxide or calcium hydroxide or baking soda, etc…
I believe based on the discussion of the definition of “room temp” we cannot assumed we all mean the same thing. Which was my point for asking the question. We’re all talking a different language.
This is true. However, it is much better defined than “mash temp”. Room temp, in pH speak, is either 68 °F or 77 °F. Usually it’s dictated by the manufacturer specification for the meter or the specifications/instructions for the solutions.
“Mash temp” is much more problematic obviously because depending on when you take your measurements it could be anywhere from lower than beta, to beta temps, to alpha temps, to mashout, etc.
It’s all good anyway you shake it as long as I give a temperature along with my reading, that way someone can recreate that or convert it to another pH at a different temperature for reference.
This is quite a interesting discussion. I use the EZwatercalculator for determining my water additions and estimating my mash ph. I’ve just started using a Millwaukee MW102 in the last few months. I’ve been measuring ph now on my last few brews. I always just stick the probe right into the mash tun and get a reading since it has the temp probe and automatic temperature adjustment. Ezwater has consistently estimated 0.3 ph higher than what measurement I got from the ph meter. The comment about the difference between room temp and mash temp readings being 0.3 got me thinking. Is my difference caused by that? What is ATC good for then?
ATC does not account for differences in hot vs. cooled wort but rather differences between cooled sample to cooled sample or cooled sample to reference solution.
Okay, interesting. I didn’t realize that. Sorry for the dumb question. I guess both are probably right on top of each other then. I’m brewing this weekend. I’ll have to take one measurement warm and then pull a sample to do a second measurement at room temp.
Not a dumb question at all. It’s a common misconception.
The main reason to not take measurements at higher temperatures is to preserve the life of the probe on the meter.
dmtaylor will say otherwise but that guy is a wacko… 
So if all of this could be distilled a little bit: Is it suggested to shoot for a mash pH at room temp of 5.4 to 5.5 which could translate to a mash temp pH reading of 5.1 to 5.2? I admit that I have been targeting a room temp reading of 5.2 to 5.3 which sounds a bit low. I am also brewing this weekend and will target 5.4 to 5.5.
Also, if I may: If someone targeted a room temp reading of 5.2 which translated to a mash temp reading of 4.9 (I’m making this up), what might the result be? Lower efficiency? Flavor impacts? Clarity issues? I hope I didn’t create material for another 16 pages of this.
I doubt that you will see a 0.3 point difference with a modern pH meter. 0.2 points is more likely. Weyermann posted data which showed that for their pH meter a consistent difference of 0.22 points was observed. Die Beerery seems to see closer to only around 0.17 points of difference as I recall (wherein hopefully he will jump in and clarify if this is not accurate), but in his case it is a cross comparison between two different pH meters, one utilized to take continuous mash temperature pH readings, and the other being a hand held unit more akin to yours and mine, and reading spot grab samples at room temp.
When this is seen, in my experience it is directly related to having taken the “Mash pH” reading too soon within the mash, and thereby having achieved a false low pH reading for the mash.
Another way to achieve a false low pH reading it to stir the sample with the pH probe while taking the reading, thereby inducing what is called “stirring error”.
And another way to get a false low pH reading is to read the pH as soon as the meters reading “stability” flag pops up. The probe needs to sit undisturbed in the Wort for a couple minutes to achieve a stable and more correct reading. The stability indicators are generally useless, but they use this feature to sell meters, so…
And yet another way to get a false low pH is to falsely believe/presume that ATC compensates for temperature, and thereby read the sample at a temperature above 68 degrees.
All of this combines to indicate that false low pH readings are vastly more commonly achieved than for false high pH readings.
But the biggest mash pH reading error of all is one related to “Confirmation Bias”. This bias generally manifests itself in a totally misplaced blind faith in software prediction, such that actual pH readings are bent and twisted and contorted by whatever means that work (hint, some ways are in the list above) to fleetingly give a meter reading somewhat in line with (or better yet, spot on with) software projection. And then write this reading down because readings conforming with software prediction make one feel good. This sort of pH reading (as deeply in error as it is) is very common. But, hey, it’s all about feeling good about your pH reading, not to mention impressing those who will also nod as they gullibly eat it up. right?
And I just thought of one more, which is the “I need to get in line and conform” pH reading bias. This bias has degrees to which one can be infected by it, but the worst degree of all goes something like: I’ve read in so many places and over such a long time period that software X is always just about spot on all the time in its prediction of mash pH, but no matter how hard I try I just can’t seem to get my own pH readings to rise to this level of conforming perfection to what obviously must be some superior level software, so rather than ever embarrass myself publicly, and in order to feel like I “belong”, I’ll just go with the software, and better yet, I won’t even bother to read mash pH’s again, but rather I’ll just keep repeating the mantra that software X is always spot on. Again, its all about feeling good, and this time its also about feeling welcomed as part of the group.
You forgot to plug your software!
I have heard that as well, but I don’t believe it! 
Correct me if I am wrong here. I usually do this when i first put the probe into my sparge liquor to get an initial reading and also after dosing it with phosphoric acid to make sure that the probe is consistently covered with a homogeneous sample. I then let it sit for at 2-3 minutes to allow the reading to stabilize, it sometimes takes a bit longer as the reading slowly changes in small amounts (I assume that is due to additional dissociation of the acid in the sample or minute temperature changes in the sample). I have heard about stirring error and try to minimize it by the above mentioned rest in the sample.
With regard to mash samples, I never stir the probe in the sample since it stabilizes pretty quickly as opposed to my sparge liquor sample.
There is nothing wrong with attempting to gain sample unification via stirring with the probe, as long as you don’t read the pH until after it sits undisturbed for awhile. There are so few ions present within water that a stable water pH reading often takes an extended period of time over which to stabilize. And due to the CO2 in the air itself, you may over time begin to see a moving target rather than stability. It is difficult to gauge a precise pH for water in and of itself.
That’s not what I was saying. Rather, that they aren’t measuring mash, but wort pH at knockout, and that it is around 5 (but quoted at mash pH so closer to 4.8 ).
As indicated above, my pH reading at 20 min over multiple brews was nearly the same than any other time in the mash. So, there must me more to this.
Regardless, I’m brewing beer at home for me and my family and friends. I’ve never once had someone say “this beer tastes like the pH was taken too soon in the mash.”
So… I’m not sure it matters. I think what does matter is doing whatever process the same way every time. Apples to Apples.
This post wins the prize for being spot on. You can’t fault success, or the ability to achieve the repeatability of such success.
PS: This reminds me of the guy who once said that you are not likely to hear your friends or relatives comment that “This beer tastes like it had low mash efficiency.”.
The only plug will be to explicitly state that mine (as for yours also) is not excluded from my listed comments, and you should never trust “any” software (mine included) over your own carefully undertaken pH readings. My comments were all meant as a guide whereby to lead you (the collective you being used throughout here) to the point of being able to trust the validity of your own pH readings, while weening you away from the belief (based upon faith alone, with a touch of a lack of self confidence on the side) that somehow math models can be superior to measured and quantified reality. When it comes to brewing they are not. What they often are though can be likened to a watched clock which is found to be right twice a day. Only for the case of software, sometimes despite its inherent flaws it finds good correlation under certain circumstances for certain procedures and certain recipes. And that leads me to another warning:
Never presume that because your software agrees in one or a scant few cases with your specific recipes, procedures, or set of circumstances, that it will thereby do likewise for all other recipes and/or sets of circumstances or procedures. Hint, it most assuredly won’t. Correlation does not imply or equal causation.
Well said