[blatz]

Hey guys

What kind of a drop should I expect to see between mash and kettle pH?

Brewed a pilsner last night and my pH meter was going haywire.  I recalibrated before mash-in, took a sample, cooled it - first reading 6.05 - huh??? recalibrated, took a reading of the same sample - 5.4 - okay! - rinsed and re-took just for good measure - 5.7??

Broke out the colorpHast strips - solid 5.3 (which really means about 5.5-5.6) - i'm okay with that.

Then in the kettle, I used my meter - 3 consecutive readings, rinsing in between - every time dead on at 5.41.

So I'm curious what the differential between mash and kettle pH is - trying to determine if I was just getting bad readings or is something else awry.

[Thirsty_Monk]

When I was doing mash tun and BK pH reading with colorpHast most of the time it was the same.
From time to time BK reading was 0.3 lower.
It was not consistent.

[mrcceo]

 Just an observation: I find the spread will vary depending on the grain bill and the amount of water salt additions. Yesterday I brewed an Oatmeal Stout with a Dublin water profile which for me requires a generous amount of salts since I have low alkalinity water. When I checked the pre-boil pH it was 5.4. The 90 min. post boil dropped to 5.05.  When I brew light colored lagers which require little to no water adjustment and have no dark roast grains the pre-boil and post boil pH are nearly the same.

[thcipriani]

FWIW I typically see a slight rise in pH after sparging - like half a tenth or a full tenth of a pH unit to kettle full. Post-boil I'll see a 2-tenth drop from kettle full, typically. For example today was:
5.37 mash pH
5.42 kettle full pH
5.28 post-boil pH

I'll see that rise in pH even though I adjust my sparge water with CRS to ~5.7.