My wife and I are home brewers that developed ACCUmash in late 2013. We believe in making home brewing easier for brewers at any experience level. For our patented product, we use calculations from the science used in the spreadsheets that many brewers mentioned above. Through iterative experimentation, we have tested and adjusted our formulations. We make it easier to brew without having to open/interpret a spreadsheet or know and understand the variability of your tap water. We understand that calcium carbonate is not very soluble and do not include more than what we believe is soluble at mash temperature and pH. Everyone of the ACCUmash recipes have been tested with multiple batch experiments. Leaning too heavily on a calcium carbonate addition would result in a failed recipe (which we had many of before establishing our final recipes).
There are two considerations here. The first is that chalk is alkaline and therefore will raise mash pH, not lower it. You can dissolve as much chalk as you want at mash pH if you add the acid it takes to do the job i.e. if you can maintain mash pH in the presence of chalk. It (the chalk) simply converts to the calcium salt of what ever acid you use, CO2 gas and water. Chalk's solubility at mash pH is not at issue. The problem with a mash is that it doesn't have the acid to get the mash to desirable pH. The brewer must add acid for most beers. If the brewer doesn't then he is relying on the specialty malts (sauermalts, roast malts, crystal malts) to supply it. In a typical pale beer mash one might have 90% base malt and 10% colored malt of say 20L. A mash of 9 lbs Crisp Maris Otter and 1 lbs Briess 40L crystal would be expected to have a mash pH of 5.6. Most would agree that that is on the margin and that 5.5 or even 5.4 would be preferable. For the former one would have to add 22 mEq of acid. For the latter 44. Thus the brewer should add nothing if he is willing to accept a mash pH of 5.6 and as much as 44 mEq of acid if he wants pH as low as 5.4.
If one adds alkali to that the mash pH will go up. It will be higher than 5.6. Suppose, for example, we added 1 gram of chalk to this mash and that the chalk dissolves i.e. that it delivers its potential alkalinity. It doesn't, as we shall see and that is ostensibly a good thing but for now lets assume that it does. It would absorb protons from the mash converting some carbonate ions to bicarbonate and some of those to carbonic acid. The pH would rise by about 0.1 point to about 5.7. As it is generally accepted that mash pH of 5.6 is marginally high one would scarcely want to go to a higher mash pH and, therefore, adding chalk to a mash such as this one just doesn't seem like a very good idea.
The second thing that is being ignored is that calcium carbonate dissolves very, very slowly at mash pH and above. If you take a beaker full of DI water, add enough hydrochloric acid to set the pH to 3 or 4, insert a pH electrode and a stir bar, add a pinch of chalk and record pH you will, initially, of course, record pH 3 or 4 and, as it takes very little HCl to set water pH to 3, expect the CaCO3 to quickly neutralize it with a sharp rise in pH. The rise in pH does occur but it takes days, not minutes. I was in disbelief the first time I saw this. I had a beaker full of a milky suspension of CaCO3 with a pH of 3 which was creeping but not galloping upwards. I thought the electrode had gone south. A moments reflection reminded me that I had seen similar behaviour in recordings of mash pH to which chalk had been added.
There are three reactions that must take place for protons to be absorbed:
1) CaCO3 + H2O ---> Ca++(aq) + CO3--(aq)
2) H+ + CO3--(aq) ---> HCO3-(aq)
3) H+ + HCO3-(aq) --->H2CO3
Since reactions 2 and 3 take place instantly in the titration we do when measuring the alkalinity of a water sample we conclude that it is reaction 1 which is holding things up. Even the tiny particles of the flour like 'precipitated chalk' we buy take a long time to go into solution (the smaller the particle the larger the ratio of surface area to mass so that you would expect smaller particles to dissolve faster than larger ones). If you continue your experiment incrementally adding acid to the suspension sufficient to bring the pH down to 2 or 3, waiting for it to react to raise the pH back up to 6 or 7, adding more acid... eventually the chalk will be consumed and the liquid will turn clear. That doesn't mean all the chalk is dissolved. It just means the remaining crystals are too small for you to see. pH will continue to climb overnight (I haven't gone much longer than that in these experiments) proving that there is still CaCO3(s) in suspension.
The conclusion to be drawn from all this is that you have decided to add chalk to mash in order to withdraw protons (raise mash pH) although in the case of pale beers (and even some stouts) this is the exactly the wrong thing to do (most pale beers require acid) but only a small fraction of the added chalk actually does so. Thus you
ostensibly get away with making this mistake. But that un-reacted chalk is still there or at least some of it is. We presume that the larger flour particles get trapped in the sparge but we are fairly certain that microcrystals make it through. These get to do their pH raising damage later on in the sparge, kettle and even into the fermenter. Another conclusion is that in a grist where alkali is desired (because the roast/high kilned malts deliver more protons at the desired pH than the base malt can absorb) chalk is a poor choice because it doesn't absorb all the protons the stoichimetry says it should until the beer is long out of the mash tun. In such cases one uses bicarbonate or calcium hydroxide.
These phenomena are well known in the brewing community if not fully understood. If you try to sell a product that relies on a methodology that is no longer accepted you will only be likely to sell it to brewers who are not up on the current understanding.
We invite you to try the product and contact us with any feedback you may have as we are always looking to improve. We have gained a significant amount of information from brewers on forums just like this.
I suppose the comment that goes here is that many brewers have tried using chalk and phosphate buffers in their brewing and have found them wanting. I definitely am behind the KISS principle for beginning brewers and direct most of them to the Primer in this forum:
https://www.homebrewtalk.com/showthread.php?t=198460
which says, in essence, add a gram per gallon divided between calcium chloride and calcium sulfate depending on how much sulfate you like and use sauermalz or not depending on whether the beer is pale or dark. There are a few more style related tweaks there as well. Lots of brewers have used the approach with success and so there is a good chance that if you sell prepackaged mixtures of calcium chloride and sulfate (usually sold as 'Burton Salts') without chalk or phosphates they would be able to use them successfully as well. But it needs to be understood that this will not result in the best beer but only a decent beer and, if one is lucky, good beer. The best beer is realized by careful measurement of mash pH (the sine qua non for the best beers) and experimentation with stylistic ion levels. This, of course, in addition to scrupulous attention to all the other detals. "Accurate" as implied by the product name, does not really fit the KISS approach.
We are currently building our website, accu-mash.com, and will be addressing many of the questions and concerns on this forum. We hope to have the website live within the month. Thank you for your interest in ACCUmash.
We do try to keep an open mind.
