Mash PH

[jim42]

Hello,
I've been having trouble with the new mash ph feature.  The mash ph that the software predicts is always higher than it actually is when I measure it (actual ph is usually 0.2-0.3 lower).  What's odd is that the first couple times I used the software, it correctly predicted the mash ph.  I thought maybe my water changed so I did a test with my LaMotte kit.  It came back with slightly higher alkalinity but only by 10 ppm and slightly higher Cl but only by 5 ppm.  I work at a LHBS so I am careful to make sure the grains I enter in BeerSmith are what I actually brew with (manufacturer, lovibond, etc).  All my volumes and losses are inputted correctly.  Any tips on what I can do to get accurate mash PH predictions?  Thanks!

[Oginme]

No pH prediction model is perfect.  If you want to waste a few days, you can jump over to HBT and read all about the different models as people argue about which one is right or wrong -- complete with many differing theories behind their stances.

My own experience shows my results to be similar to yours.  I am typically 0.2 pH units lower than what BeerSmith predicts.  In fact, it is so consistent that I can set my pH target in BeerSmith to 5.6 and reliably attain a mash pH (at end of mash) of 5.4 +/- .05 pH units.  Being a practical engineer and seeing an offset which can be predicted, I do just that -- aim for the target that I know will end up with the actual number I want.

In the end, as long as you are close to the pH range for optimal enzyme behavior, you will get adequate extraction and conversion of the starches to sugars. 

[archibeckmj]

I have had the same experience.  I generally do not rely on the recommended acid additions or my pH will be 0.3 to 0.4 lower than desired.  Glad to hear I am not the only one.

[Warphine]

I had no idea that this was a thing for other people too! Great to know. Next time I'll add 0.2 - 0.3 as an offset.