• Welcome to the new forum! We upgraded our forum software with a host of new boards, capabilities and features. It is also more secure.
    Jump in and join the conversation! You can learn more about the upgrade and new features here.

Estimated mash PH

Deunken Minoutaur

New Forum Member
Jul 18, 2017
Reaction score
Hi I new to both homebrewing and beersmith would like some help with this issue:

Is the estimated mash ph calculated by the software at room temp or at mash temp??

Beersmith gave me an estimated 5.6 mash ph, i got 5 at mash temp and 5.2 at room temp.

Would you consider a difference if 0.4 to 0.6 ph difference between estimate and actual to be within the expected margin of error or is it more likley that I am doing something wrong??

pH specifications are always at room temperature. That's where you measure pH if you want an accurate reading.
No pH estimation can take into account all the aspects of your water or the variability of contributions from the grains.  That said, you should normally come within a tenth or so of the estimate.

When did you draw the sample for pH reading.  I do BIAB and mix the grains in thoroughly for 10 minutes before taking a small sample for a pH test.  I also take one at the end of the mash, and I typically get a drop of about 0.2 points from beginning reading to end reading.

Also, make double sure that your pH meter is calibrated accurately.  This is usually the biggest cause of erroneous readings.

The specification of "room temperature" is also a bit vague. Which room, and when? I generally take a sample, put in a small metal cup and cool it down in an ice bath until it is somewhere down in the 70s, then use my pH meter. I don't know if there is much difference between 65 (my room temperature in winter) and 85 (my room temperature in summer). I assume that there is little difference or else people would be specifying a more precise temperature at which to make the measurement.

For purposes of consistency, I always aim for standard laboratory conditions of 20C/68F for taking pH readings. 
I am using a Hanna instruments PH meter with temp correction up to 145f , took reedings at 4 time intervals during my 90 min mash and all gave a ph reading of 5, 5.2 at cooled sample (room temp of around 70f) . So i am pretty sure my actual ph readings are correct.

I do understand that a mash ph of 5.2 and 5.6 (cooled sample) is nit a big deal. Just trying to understand what is off for future projects.
pH should always be taken at room temperature.  The temperature compensation for a pH meter is not a correction of the pH reading for temperature but an adjustment for the electronics inside the probe to compensate for the temperature. A pH reading at 145F will not be the same pH of the wort at 68F and the ideal activity range of the enzymes are given at room temperature in the literature.