Author Topic: Water Treatment - Questions on Reducing Alkalinity  (Read 969 times)

Offline beckx213

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Water Treatment - Questions on Reducing Alkalinity
« on: November 11, 2017, 12:59:47 PM »
I recently moved from Madison, WI to Rome, Italy and I'm having some issues with my brewing water.

While previously living in Madison, WI I transitioned from brewing with my tap water to brewing with reverse osmosis water due to the fact that the tap water was very high in alkalinity and it was having a detrimental impact on the flavor of my beer and my mash efficiency.

Now that I'm in Rome I have less mobility as I am without a car, and I decided brewing with the tap water was the only way to go. The following is a copy of a report of the water I'm working with:

Ca: 101.2 ppm
Mg: 17.5 ppm
Na: 7.0 ppm
SO4: 17.4 ppm
Cl: 9.1 ppm
HCO3: 398 ppm

As you can see, the water is VERY high in bicarbonate. The first couple of brews that I've done I've adjusted my water with lactic acid to achieve my desired pH for mashing. As a result, all of the beers I've brewed this way have that lactic "twang."

After thoroughly reading Martin's wonderful post on 'Decarbonation by Boiling,' I've decided to go that route. Using Martin's formula, my calculations indicate I should have enough Calcium to reduce the bicarbonate from 398 ppm to ~90 ppm assuming all of the Ca is converted to CaCO3. Does this seem reasonable?

Secondly, I did a bench top test by boiling 1 L of tap water in a small pan and I'm finding that after cooling the pH of the water increases from around 7.5 from the tap to 7.9 after boiling. Is this normal?

Any other advice? Thanks.

Side Note: I'm filtering the tap water through an activated carbon filter to remove chlorine. 

Offline hopfenundmalz

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Re: Water Treatment - Questions on Reducing Alkalinity
« Reply #1 on: November 11, 2017, 05:01:58 PM »
Your other minerals are low, so adding gypsum or CaCl2 will add Ca to precipitate more bicarbonate.

I will defer to Martin as to how much.
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Offline hackrsackr

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Re: Water Treatment - Questions on Reducing Alkalinity
« Reply #2 on: November 12, 2017, 03:46:28 AM »
The boiling likely precipitated some calcium. That could explain the slight pH rise.

Alkalinity can be reduced with acids, or the addition of calcium hydroxide (slaked lime) as well.


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Offline Richard

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Re: Water Treatment - Questions on Reducing Alkalinity
« Reply #3 on: November 20, 2017, 09:46:16 PM »
Acids will lower your pH, but calcium hydroxide is a base (it releases the OH- ion) and will raise your pH, not lower it.


Offline hackrsackr

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Re: Water Treatment - Questions on Reducing Alkalinity
« Reply #4 on: November 21, 2017, 03:56:40 AM »
The boiling likely precipitated some calcium. That could explain the slight pH rise.

Alkalinity can be reduced with acids, or the addition of calcium hydroxide (slaked lime) as well.


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The ph drop was referring to boiling as the method of alkalinity reduction, which is what the OP did. It wasn’t referring the use of Calcium Hydroxide.

The second part of the statement was just offering alternatives strategies for alkalinity reduction, which the OP asked for. Calcium Hydroxide will raise the pH of the water, that’s how the alkalinity reduction works. The Ca(OH) converts bicarbonate to carbonate, which then combines with calcium and precipitates out as CaCO3. The pH will have risen, but your hardness and alkalinity will have fallen.


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Offline mabrungard

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Re: Water Treatment - Questions on Reducing Alkalinity
« Reply #5 on: November 21, 2017, 01:23:35 PM »
Raising the pH of a solution to the point that certain salts precipitate, is the purpose of the calcium hydroxide. In this case, the calcium and bicarbonate in the tap water can be precipitated by raising the pH above 11. The water becomes cloudy with precipitating calcium carbonate and it is allowed to settle to the bottom of the vessel. The clear water is decanted off the sediment and the water is typically initially acidified by bubbling air through the water column or through air stripping. CO2 from the air combines with the water to produce carbonic acid and neutralizes the excess hydroxyl ions in solution. That neutralization works only to a certain degree. The remaining hydroxyl and carbonate ions are neutralized with an acid addition.

This process works well in certain waters. Its laborious and time consuming, but its otherwise simple.
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Offline hackrsackr

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Re: Water Treatment - Questions on Reducing Alkalinity
« Reply #6 on: November 21, 2017, 01:50:25 PM »
Well bicarbonate HCO3 isn’t technically precipitated, but it neutralized though by losing the hydrogen ion to the hydroxyl ions leaving CO3, which then bonds to Ca ions and precipitates CaCO3. The hydrogen stays in solution. Semantics, maybe...

If the OP hasn’t read Kai’s page on slaking as an alkalinity reduction method, definitely check it out. He does a great job of explaining the slaking process, as well as many other topics.

http://braukaiser.com/wiki/index.php?title=Alkalinity_reduction_with_slaked_lime


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Offline mabrungard

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Re: Water Treatment - Questions on Reducing Alkalinity
« Reply #7 on: November 21, 2017, 01:58:08 PM »
Semantics, definitely! 99% of the readers here could care less about our minutia. Maybe half of the readers would appreciate that both calcium and bicarbonate are reduced by the process, regardless of its actual mechanics.

Welcome to the 1%.
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Offline hackrsackr

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Re: Water Treatment - Questions on Reducing Alkalinity
« Reply #8 on: November 21, 2017, 02:12:45 PM »
What are you talking about? People love minutiae. That’s why they come here. That’s why so many people have read the link I posted. 

Yes HCO3 is reduced, not precipitated. You shoulda said that the first time.

Welcome to the wrong end of Wheaton’s Law! ✌️


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Offline HoosierBrew

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Re: Water Treatment - Questions on Reducing Alkalinity
« Reply #9 on: November 21, 2017, 03:32:12 PM »
What are you talking about? People love minutiae. That’s why they come here. That’s why so many people have read the link I posted. 

Yes HCO3 is reduced, not precipitated. You shoulda said that the first time.

Welcome to the wrong end of Wheaton’s Law! ✌️


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Just to be clear, are you really arguing with Martin about WATER ?  ;)
Jon H.

Offline hackrsackr

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Re: Water Treatment - Questions on Reducing Alkalinity
« Reply #10 on: November 21, 2017, 08:22:36 PM »
I didn’t argue with Martin about WATER at all. I pointed out an error in his synopsis of the method. There is nothing to argue about, it’s basic chemistry.


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