Unfortunately, most brewers will find that chalk does not work in a timely fashion and effectively buffer mash pH. I strongly advise against using chalk unless it is fully predissolved with CO2 pressure. An assumption of the chalk producing half of its calculated alkalinity is quite risky and I have had dozens of brewers complain that chalk didn't work at all. DON'T USE IT!!!
Martin, I remember when we first started this discussion about using slaked lime over on the Homebrewer's association board. It was after I found that chalk behaved oddly. But I'm not ready to embrace this adversity against using chalk that is simply based on experiments regarding mash pH and not actual sensory experiments.
Yesterday, after I wrote my replies to MG I started thinking about this some more. Especially since I knew others would scoff at my advice of adding that much chalk. I started to wonder if we have become too obsessed with he pH of the mash. That we are leaving the impression unless your pH is in that range and you do water treatment as the experts tell you to do, your beer will be not as good as it could be.
I went back through my notes and the 2009 Doppelbock that everybody at the 2010 NHC raved about was brewed with R/O water that had 3.5 g of chalk in both the mash and sparge water. That's a total of 7g of chalk for a 5 gal batch. I have made many great Schwarzbiers with chalk. I even have a documented side-by-side experiment where I used dissolved and undissolved chalk:
http://braukaiser.com/blog/blog/2009/11/24/undissolved-vs-dissolved-chalk-in-the-brewing-water/
As much as I would have liked to find that dissolving chalk makes a better beer I was not able to find enough taste difference between the two beers to make that point.
I start to wonder if we have gone too far by basing a major part of our brewing water treatment advice solely on how to get that mash pH to a magic number, especially now that mash pH prediction has become widely adopted and is fairly accurate. Since chalk is a bit odd in its behavior let's just toss it out and replace it with pickling lime. But where are the side-by-side experiments between a beer brewed with chalk and the same beer brewed with pickling lime? I have lots of results from mash pH experiments mostly because I like that I can measure pH and don't have to rely on subjective sensory perception. The intend of all these experiments is, and was, to gain insight in what affects mash pH. No more no less. But what's missing are experiments that show which target pH or water treatment in general. Those are more difficult since you have to brew a whole beer and not just a small mash sample.
I also start to wonder if alkalinity in the sparge water or kettle is all that bad. In Germany it is common practice to use the same water for mash and sparge. If you mash with high alkalinity water you also sparge with it. And that may have an effect on the character of the beer. Higher sparge pH may extract a few more tannins which, to some extent, can contribute to a more robust beer character. Decoction is known to increase tanning extraction, for example. The alkalinity in the spare water also increases the boil pH, which may be beneficial for darker beers. Based on that I'm actually rethinking the idea of using R/O water for sparging and my alkaline tap water for mashing. I think I should use both for sparging and mashing.
I'd have to classify chalk in the same category as 5.2 Stabilizer. It works great for those that don't check their mash pH and doesn't work at all for those that do check pH. The only plus for using chalk is that it doesn't add a load of sodium to your water.
I don't disagree with that and consider it doubious at best.
Regarding adding chalk or any alkalinity increasing minerals to the mash, it is not appropriate to add those minerals since the best sparging water is going to have LOW alkalinity.
back to my earlier point. What is this based on. Note that you say the best sparging water is going to have LOW alkalinity. How do yo define the best.
I noticed a comment about someone adding both acid and chalk to the mash. Since those additions will counteract each other, it makes no sense to add both. Add one or the other, not both. The free version of Bru'n Water doesn't have the extra warnings and guidance that the supporters version has. The free version is just to see if you like it enough to become a supporter.
That was a mistake that MG made and which I pointed out. As brewers get more familiar with brewing water treatment they'll learn that adding acid and alkalinity generally doesn't make sense.
I didn't know that there is also a paid version for Bru'n Water. Good to know.
Kai
