I brewed a Belgian Blonde over the weekend, and it consisted of mostly Pils malt. My tap water is, sort of, "middle of the road." (I can't remember the actual PH without looking it up) It works well for everything from light Pales to Stouts. Anyway, because I was using Pilsner malt (first time) I mashed with distilled water. I sparged (batch sparge) with a mixture, about 60-40, of tap to distilled. My question: Does the water PH matter after the mash is done? When the sparge starts, I raise the temp to 70 deg, thus stopping the enzyme activity. Thoughts?
It certainly matters during the ferment but if you hit your mash PH between 5.2 to 5.6ish, the PH should drop to the correct levels during the boil. As an aside, why exactly did you elect to use distilled water? Did you use anything like gypsum or calcium chloride to build up the calcium level to at least 50 ppm? From what I understand, calcium is a co-enzyme factor for amylase enzymes so you might be hurting your efficiency. Also, calcium helps with flocculation.
Calcium (and Mg by half) lower the mash pH by combining with phytin in the malt and producing an H+ ion. Calcium also aids yeast health. Finished beer pH is also important. Gordon Strong covers this in his book.
Yeah, I also wondered about the use of distilled water. Distilled and reverse osmosis water should rarely be used from my understanding (unless you use these as a base to build your own water composition).
The OP didn't give his tap water profile numbers but he stated he used a 60/40 ratio of tap to distilled. He just effectively softened his water. Depending on his tap water numbers and since he reported using primarily pils malt he may be right on the money for his mash pH and critical mineral quantity. Edit: From his post he it looks like he may have done the 60/40 ratio for his sparge only. Your distilled question still applies here.
Actually, he said he mashed with distilled and sparged with the 60/40 ratio. Generally speaking, not an ideal mash situation.
pH also matters after this mash is done in terms of controlling the pH. some say (I haven't seen any definitive proof on it though) that the sparge water pH should be 5.5 to 6.0 to avoid extracting tannins from the grain should the grain pH get too high. I always adjust my sparge water pH with a small amount of lactic acid for this reason.
I sparge (or mashout when doing no sparge) with plain distilled water. As long as the mash pH was in an acceptable range, distilled water isn't going to move it.
My tap water: Calcium Hardness is about 120-130 ppm (CaCO3) Magnesium hardness is about 40-50 ppm (CaCO3). So my thought was, since I batch sparge, I would be lowering my mash ph while mashing but balancing the calcium and the ph when I sparged. Thus winding up with a decent mix for boil and fermentation. In hindsight I probably should have done a 60-40 mix for the mash and sparge. I don't have a ph meter so I'm not sure what my levels were. Also, I never thought I would have to say this but, I broke my hydrometer right before brewing. So I don't know the efficiency.
Beersmith recently posted a very informative interview with John Palmer where he covers pH (and other attributes of water) across the whole brewing process. It's long and gets down into the weeds a few times, but lots of useful info otherwise: http://beersmith.com/blog/2013/05/28/beer-brewing-water-with-john-palmer-beersmith-podcast-60/
