Mash thickness affecting pH

[Dan]

I have been using palmers spreadsheet for calculating mash pH
http://www.howtobrew.com/section3/chapter15-3.html

When i do an infusion mash I often need to top up with boiling water to maintain the temp. I find the mash pH increases (away from the optimum) with the further dilution of the mash, even though the "top up" water has recieved the same treatment as the mash liquor.

This isn't really a big problem, but just for interests sake, is there a calculation to model mash thickness against mash pH?

[Jim]

I don't know of any standard calculation for this, and reactions affecting pH aren't as simple as, say, titratable acidity as used in winemaking.

I find that adding water to make the mash thinner can help me achieve the correct pH, as my mashes are often too acidic otherwise.

[Dan]

cheers guys.

I think i'll follow daabs advice, eliminating the need for topping up. I can usually hit my required pH before diluting with boiling water.

buffering capacity of the mash which could make a mockery of any calculations.

yeah tell me I've never found this area a straight forward one.
the only way i get consistant results is by sticking to a tried recipe. as soon as i formulate a new one from a wildly different style Its back to trail and error. all the calculations i found so far will put the pH in the right ball park at least, but as for fine tuning goes, I think constantly diluting the mash is making a rod for my own back.

[Vossy1]

Another option...ph 5.2....yes I'm lazy