With some prodding from a fellow homebrewer (you know who you are!), I have put together a simple spreadsheet for calculating mash pH. The equations used in the spreadsheet are discussed in the two papers introduced in the previous two posts of this blog. The spreadsheet is not unlike others that are out there (think EZ Water, Brun Water, and Kaiser Water), but it is not as extensive in that (for this first version, anyway), it only deals with estimating the pH of the mash. This does, however, make the spreadsheet quite simple and (I hope) quite straightforward to use.
One thing the sheet assumes is that you know the ion concentrations (in ppm) associated with your brewing water. If your water report does not give these in a straightforward manner, I suggest you search around on the web to first figure out how to convert your information to ppm of the individual ions.
The outline of the spreadsheet is as follows. From your grain bill and strike water volume, the pH that your mash would have if you were to use distilled water is calculated. Next the spreadsheet takes into account any ions in the strike water that can affect pH. These ions are Ca^(2+), Mg^(2+), and HCO_3^+. After this you can enter any salt additions that you wish, and pH is calculated again taking these into account. Lastly, you have the option of several acid additions that will also affect pH. The bottom-line pH value is your estimated pH. Along the way you may find the comments attached to various cells useful.
One feature you may find lacking is that this spreadsheet does not deal with CaCO_3 (chalk) additions. This is intentional. First, the addition of chalk is (i) really never necessary, and (ii) somewhat problematic in that chalk only fully dissolves in the presence of elevated CO_2 pressure. If you really needs to raise the HCO_3^- (bicarbonate) level of the brewing liquor, a little NaHCO_3 will go a long way, as the spreadsheet will calculate for you.
As always, thoughts, comments, and questions are always welcome. Cheers!