Calcium carbonate precipitation and "milky" beer

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seanppp

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I have hadd good luck on this forum with this sort of question (many thanks to Martin Brungard in particular!) so I thought I'd ask this one:

I work at a nanobrewery in a place with high calcium and bicarbonate source water. We pre-heat the water (to ~175F) the night before we brew, and a ton of calcium carbonate precipitates out by the time we arrive in the morning. The other day we only brought it to 155F, and when we came in the water looked milky. It was really weird, but then I thought maybe the calcium carbonate was formed in the water but didn't fall out. Is this right? If so, could someone explain the chemistry?

Thanks!
 

mabrungard

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I'm betting that the lower heating drove off less of the latent CO2 and there was only a partial and weak production of calcium carbonate that formed very small flocs that lingered in the water as the haze. Forming larger flocs helps speed precipitation. A nice technique that AJ details, is to add a dose of powdered chalk to the water (I know it sounds counterproductive) to help form larger flocs that precipitate faster. All that extra chalk that was added will only precipitate out and not add to the calcium or carbonate content of the water.

One thing I would be very concerned with in the case above, is that the degree of alkalinity reduction was also less than typically observed. If the brewer has a routine and doesn't account for that extra alkalinity, then the resulting pH's might have been elevated. Might not be a desirable result.
 
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seanppp

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Martin, you rock man! Okay, so that's what I had assumed. Good idea with the chalk, too. I'll remember that.

Thanks again!
 
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