hist-brewing: calcium carbonate

BrewInfo brewinfo at xnet.com
Tue Feb 1 11:32:20 PST 2000


Ox writes:
>As a followup to my posts of a couple weeks back on water chemistry, I have 
>since obtained a different source of water, and figured out what I would have 
>to do to the water to get it to approximate the mineral content of water from 
>London.  One of the steps was to boil the water while airating it to 
>decompose the bicarbonate into calcium carbonate, which will precipitate out. 
> I have done this.  It does indeed clump together.  It's suppose to fall to 
>the bottom.  Some of it does this - much of it is still suspended in 
>solution.  I did this yesterday morning.  It's been about 30 hours now.  How 
>long do I have to wait for it to clear?  

Clump?  Hmmm... calcium carbonate tends to precipitate quite quickly, in
my experience.

>Noonan's book said to cover it to keep CO2 from recombining with the water 
>and making the bicarbs redissolve.  I have done this too.  If I let it go too 
>long to precipitate out, I will be undoing all the work I have done so far.  
>Anyone else done this?  Do you have any tips?

Well... Noonan is good for brewing technique, but his science is suspect at
best.  "Covering" a container won't keep CO2 out of the headspace and therefore
will not prevent the CO2 from redissolving in the water.  It is the driving
off of the CO2 which raises the pH so that the water cannot keep the CaCO3
in solution.

The problem is that unless you retest your water for CO3, you can't tell
how much carbonate you removed by boiling.  Therefore, you have several
choices:

1. Don't sweat the details.. just get the water sort of close and brew
from there.

2. Dilute your water of known ion content with distilled water... this
way you know pretty much exactly what your waters' ion makeup is and then
add back what you need via salts.  This might sound easy, but sometimes
the ions just don't add up... sometimes you can't get the calcium up
high enough without too much chloride or sulphate.

3. Be pragmatic.  Only mess with the ions that actually affect the
flavour of the beer (sulphate accentuates the bitterness and gives
a long, lingering bitterness to the finish and chloride makes the
beer rounded and soft).  Unless you have excessive iron, sodium, or
sulphate or really, really high carbonate levels, you can simply add
calcium sulphate to get the sulphate right and then brew.  Alternatively,
you can boil your water to remove *some* of the carbonate (an unknown
amount, as I said before), let it cool an hour or two and then decant
off the sediment.  Then add calcium sulphate if the sulphate is too low
or distilled water if the sulphate is too high.  You may want to add
a little calcium chloride or sodium chloride if your chloride is too low...
choosing which you use depends on your calcium and sodium levels (don't
forget to account for any calcium added via calcium sulphate).  Then you
brew... but watch the pH and carefully add some calcium carbonate if the
pH is too low (shoot for 5.3 to 5.6) or some lactic acid if the pH is
too high.

I started brewing doing #1, then started doing #2, but now I do #3.
Brewing water chemistry is basically sulphate, chloride and pH (presuming
none of the other ions (like sodium) are way too high).

Al.

Al Korzonas, Lockport, Illinois, USA
korz at brewinfo.org
http://www.brewinfo.org/brewinfo/

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