[Silver_Is_Money]

This is something I don't understand. 

Once dissolved, carbonate can exist in water in three different forms (aqueous carbon dioxide/carbonic acid, bicarbonate, and carbonate) depending on the pH of the water.  The chart you posted shows this, and there is a similar chart on page 66 of Water.  That chart also shows that below a pH of 4.3, all of the carbonate has converted to aqueous CO2/carbonic acid.

However, I don't think that it follows to say that you cannot eliminate all of the bicarbonate in the mash (whether through reactions between phosphates in the malt with calcium and magnesium that release hydrogen protons which react with dissolved carbonate to form water and CO2 gas or through the addition of acid with supplies the necessary hydrogen ions) without bringing the pH down to 4.3. 

I can prepare a mash with distilled water (that contains no bicarbonate) and have the pH settle at 5.4.  Similarly, I can prepare a mash with water that has 100 ppm bicarbonate and add enough acid to bring the pH to the same 5.4.  In that second scenario, I have neutralized all the alkalinity that was due to the bicarbonate content of the strike water, haven't I eliminated all of the bicarbonate?

Or we talking about two different things here (the form in which carbonate exists in water given a particular pH vs. bicarbonate, residual alkalinity, and its effect on mash pH) or am I missing part of the larger picture?

This is quite easy to explain. 
1) Distilled water simply has little to no bicarbonate species to begin with.  It settles in at about 5.8-5.9 pH due to the CO2 in the atmosphere reaching an equilibrium state with the water whereby entering CO2 combining with water and forming Carbonic Acid (H2CO3) is in perfect balance with Carbonic Acid dissociating back into CO2 and water.  CO2 + H2O ⇆ H2CO3

2) Natural water with true HCO3- Bicarbonate ions acts as I've previously outlined.  It's Bicarbonate is sourced primarily from extremely long term exposure to Calcium Carbonate and Magnesium Carbonate bearing rocks.

[Village Taphouse]

In that second scenario, I have neutralized all the alkalinity that was due to the bicarbonate content of the strike water, haven't I eliminated all of the bicarbonate?

Right.  This is what I originally asked about.  I am not sure if I neutralize the bicarb with acid and get to a mash pH of 5.4 if the bicarb is GONE or if it's just at a lower ppm. 

In the end, I no desire or reason to build my water up.  The numbers are modest enough to work for almost all styles and an easy dilution with distilled seems easy to do when necessary.   

[Silver_Is_Money]

Right.  This is what I originally asked about.  I am not sure if I neutralize the bicarb with acid and get to a mash pH of 5.4 if the bicarb is GONE or if it's just at a lower ppm

Fortunately two old (one circa 1950's - the other circa 1960's) peer reviewed brewing industry documents I've uncovered had addressed this and concluded that at even as high as 50 mg/L (ppm) Bicarbonate in ones mash and/or sparge water it is most likely harmless, and that by 25 mg/L it is 100% assuredly harmless.  We have generally been led astray by some more recent and unfounded (as in amateur level and/or not peer reviewed, yet touted long enough to become gospel) notion that bicarbonate is something that must (for mainly the brewing of light colored lagers and ales) be fully eliminated.  The same (generally home brewing oriented) literature generally presumes (incorrectly) that such complete elimination is achieved via acidifying ones source water to pH 5.4 - 5.6.

Since pH 5.4 more factually represents ~90% bicarbonate reduction, ones source water would need to exceed 500 mg/L bicarbonate whereby to also exceed 50 mg/L of same when acidified to pH 5.4.  But where there is that much bicarbonate there are also far and away most likely going to be massive amounts of the likes of magnesium and calcium and iron and manganese, so using such water (which will generally be well water) "as is" (albeit for acidified to pH 5.4) is in most cases not an option for reasons that are other than the acid addressable high bicarbonate.

[erockrph]

So permit me to pull us deeper down this rabbit hole. Most of the discussion regarding bicarbonate, and the equilibrium of carbonic acid/bicarbonate/carbonate with respect to pH has been looking at strike water and mash pH. But if we're concerned with the flavor impact of bicarbonate on beer, then you also can't overlook the fact that we boil after the mash. This drives off all of the CO2 that is dissolved as carbonic acid. And since there is an equilibrium, this leads to more bicarbonate being converted to carbonic acid, and more of that CO2 being boiled off, etc. I'm sure that the chemistry is not as straightforward in boiling wort as it is in water, but generally you end up in the 50-80ppm range for bicarbonate when you pre-boil brewing liquor IIRC. The remainder of CO2 either boils off or binds with calcium (as carbonate) and precipitates out as chalk.

If you're looking into the flavor contribution of bicarbonate, you would want to consider the amount in the finished beer, which should be considerably lower than what you started with.

[Village Taphouse]

Guys, thank you again.  Yes, the flavor contribution (or I could say "mouthfeel" contribution) interests me.  In that Gordon Strong link, he mentioned disliking "alka-seltzer" beers (or someone else mentioned that) and I wonder what that is referring to... high bicarbonate or something else?  If it's something else then what is it?  If it's high bicarb then how high are we talking?  Is he referring to a pale lager made with source water that had 400+ppm of bicarb?

Also, for the record I'll post my numbers.  They're all modest except for bicarb so there is not a ton of Magnesium, etc.  Ca 34, Mg 13, Na 12, Cl 21, SO4 27 (that's 9x3 so maybe that's SO4-S) and bicarb 138ppm.  I have made two pale beers in the past month where I diluted with 2 gallons of distilled water and I saw better hot break and I had an easier time moving the pH with less acid.  I think this is a good step and getting gallons of distilled water is easy and inexpensive.  I might start doing this on every batch going forward and pay close attention to the results.  Eventually I might find that it's not necessary on all styles.  Cheers and thanks again.

[mabrungard]

For readers of this thread, be aware that Gordon Strong is not detesting the flavor of bicarbonate, he’s detesting the effects of bicarbonate in beer. Bicarbonate is essentially flavorless in water. Now let’s move on to the real issues.

Having a modest bicarbonate content is okay for most brewing. I had a level similar to Ken’s in my Tallahassee water supply. I never detected lactate in my resulting beer that I made there. But I have a typical taste threshold for lactate. There are some people that are supertasters with respect to lactate and they might have had another opinion. That level is getting up there.

If YOU feel that you can taste lactate when employing lactic acid in any of its forms, you should limit the lactic addition and employ another acid to supplement or replace. Using other acid is okay, but I find that using some form of lactic acid is helpful in creating authentic tasting Continental European beer styles. British and American styles can be made without lactic acid.

[narcout]

In that second scenario, I have neutralized all the alkalinity that was due to the bicarbonate content of the strike water, haven't I eliminated all of the bicarbonate?

Right.  This is what I originally asked about.  I am not sure if I neutralize the bicarb with acid and get to a mash pH of 5.4 if the bicarb is GONE or if it's just at a lower ppm. 

I feel like this question is still outstanding, and also there has been some divergence in the discussion between (i) acidifying strike water and (ii) residual alkalinity/mash pH.

If you reduce the mash pH to at or below the pH that would have resulted if you had used 100% distilled water with no bicarbonate as your strike water, what is the mechanism by which bicarbonate can still be present?  Put another way, if you have reduced residual alkalinity to zero (or below), have you converted all the bicarbonate to water and CO2?

I get that it doesn't really matter for all practical brewing purposes, but I want to understand it just for the sake of understanding it.

[Village Taphouse]

Martin, thank you for joining and replying.  I do not taste the acid, AFAIK.

And since Narcout likes divergence, please allow me to add one last thought.  Imagine something pilsnery or maybe an amber lager (SRM 8-9 ish) where I have added 2-3 ounces of something noble like Hallertau, Tettnanger, Spalt Select, etc. and I get a little roughness, harshness in the finish.  Is this related to the rest of this topic?  Are those noble hops reacting to leftover bicarb, my 27ppm of sulfate, etc?  That piece might not even be closely related but my untrained and unscientific mind wonders if there is a connection and I also seem to remember a story (probably unsubstantiated) about noble hops and either sulfate or bicarb clashing.  Cheers again.

[erockrph]

In that second scenario, I have neutralized all the alkalinity that was due to the bicarbonate content of the strike water, haven't I eliminated all of the bicarbonate?

Right.  This is what I originally asked about.  I am not sure if I neutralize the bicarb with acid and get to a mash pH of 5.4 if the bicarb is GONE or if it's just at a lower ppm. 

I feel like this question is still outstanding, and also there has been some divergence in the discussion between (i) acidifying strike water and (ii) residual alkalinity/mash pH.

If you reduce the mash pH to at or below the pH that would have resulted if you had used 100% distilled water with no bicarbonate as your strike water, what is the mechanism by which bicarbonate can still be present?  Put another way, if you have reduced residual alkalinity to zero (or below), have you converted all the bicarbonate to water and CO2?

I get that it doesn't really matter for all practical brewing purposes, but I want to understand it just for the sake of understanding it.

The pH scale for the carbonate/bicarbonate/carbonic acid equilibrium are:

4.3 - below this pH, everything is in the form of Carbonic acid/dissolved CO2. There are no bicarbonate or carbonate ions in solution
4.3-8.3 - everything exists as a mixture of carbonic acid and bicarbonate, with the proportion of bicarbonate increasing as pH increases
6.3 - this is a buffer with equal concentrations of carbonic acid and bicarbonate
8.3 - at this value everything exists as bicarbonate
8.3-12.3 - everything exists as a mixture of bicarbonate and carbonate, with the proportion of carbonate increasing as pH increases
10.3 - this is a buffer with equal concentrations of bicarbonate and carbonate
12.3 - above this pH, everything is in the form of carbonate, no bicarbonate or carbonic acid is present

Note that these values are directly related to the pKa values for H2CO3 <> H+    +   HCO3-; and HCO3- <> H+   +   CO3(2-). This isn't related to the pH of distilled water. Also, the presence of ions like calcium and mag make this a bit less straightforward, as they can bind to carbonate and bicarbonate ions, sequestering them from this equilibrium.

[narcout]

The pH scale for the carbonate/bicarbonate/carbonic acid equilibrium are:

I get the chart, what I don't get is the how (or if) bicarbonate can still be present in the mash if you have reduced residual alkalinity to zero (which you can do in the normal mash pH range and without reducing the pH of the mash all the way to 4.3).

RA (ppm as CaCO3) = Alkalinity (ppm as CaCO3) - [(Ca (ppm)/1.4) + (Mg (ppm)/1.7]

If RA is zero, how is bicarbonate still present?

[erockrph]

The pH scale for the carbonate/bicarbonate/carbonic acid equilibrium are:

I get the chart, what I don't get is the how (or if) bicarbonate can still be present in the mash if you have reduced residual alkalinity to zero (which you can do in the normal mash pH range and without reducing the pH of the mash all the way to 4.3).

RA (ppm as CaCO3) = Alkalinity (ppm as CaCO3) - [(Ca (ppm)/1.4) + (Mg (ppm)/1.7]

If RA is zero, how is bicarbonate still present?

Because RA is just a convenient brewing calculation that doesn't directly provide the actual bicarbonate concentration. If the pH is above 4.3, then there is still bicarbonate in solution, even if it is effectively "neutralized" as far as mash pH calculations are concerned.

[Silver_Is_Money]

Chemists Barth and Zaman have shown (in a peer reviewed paper published in 2015 titled 'Influence of Strike Water Alkalinity and Hardness on Mash pH') that the contrived valuation of "RA" is pretty much a non entity and a fallacy.  If there is such a thing as RA it is highly subjectively variable since Barth and Zaman proved that the calcium and magnesium divisors themselves are variables which wildly swing in measured value from malt to malt and lot to lot.

In their peer reviewed paper, Barth and Zaman discuss that Kolbach's divisors (which in mEq terms [as opposed to ppm terms as seen in a post above] are 3.5 for Ca++, and 7 for Mg++) were arrived at by Kolbach as the measure of pH drop across both mash and boil and as measured at "knockout".  Kolbach never measured mash pH's whereby to establish his Ca++ and Mg++ divisors.  What Barth and Zaman discovered is that (for the three base malt lots which they repeatedly tested with consistent results) the previously presumed Ca++ divisor of 3.5 actually varied from about 7.2 to 14.8 within the mash in their tests, and depending upon which of their three malts they were testing.  Thus RA is literally rather impossible to predict in advance, and in addition, the mash pH suppression impact of Ca++ is roughly (and variably) half to one quarter of what one calculates if they mistakenly apply Kolbach's knock-out measured Ca++ and Mg++ divisors to the mash.

From the Barth and Zaman paper, the mash stage measured Ca++ divisors which most presume (incorrectly) to be fixed at 3.5 were actually:
Pilsner malt divisor = 14.8
Pale Ale malt divisor = 7.2
Munich malt divisor = 12.2

Who knows what wildly variable divisor values they would have come up with for other malt brands, lots, types, growth regions, varietals, or crop years....

[narcout]

Because RA is just a convenient brewing calculation that doesn't directly provide the actual bicarbonate concentration. If the pH is above 4.3, then there is still bicarbonate in solution, even if it is effectively "neutralized" as far as mash pH calculations are concerned.

If that's the answer, then I'm clear.  Thanks.

I also seem to remember a story (probably unsubstantiated) about noble hops and either sulfate or bicarb clashing. 

People have posted about noble hops and high sulfate levels not being a great combination.  I've never tested it and have no idea if it's true.

[denny]

Because RA is just a convenient brewing calculation that doesn't directly provide the actual bicarbonate concentration. If the pH is above 4.3, then there is still bicarbonate in solution, even if it is effectively "neutralized" as far as mash pH calculations are concerned.

If that's the answer, then I'm clear.  Thanks.

I also seem to remember a story (probably unsubstantiated) about noble hops and either sulfate or bicarb clashing. 

People have posted about noble hops and high sulfate levels not being a great combination.  I've never tested it and have no idea if it's true.

I guess then you'd have to quantify "high sulfate level"