Totally Confused About Residual Alkalinity

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chally

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I'm just getting started down the custom water profile path. I've read the primer, and I think I get the basics with respect to stuff like mash pH and chloride:sulfate ratio. I don't have a great source for RO or distilled water, so I try to make my tap water work (with some minor additions, and dillution where really needed).

Throughout this process, however, I keep bumping into the notion of residual alkalinity and the information seems to be all over the map. Some say it's important, some say it's not.

I recently tried to design a water profile for an oatmeal stout using a target profile from the Bru'n Water Calculator. It ended up saying that my mash pH was too high (~5.6) AND my RA was too low (~48). I can't figure out how to save one without sacrificing the other. I suspect it's the RA that has to be sacrificed, but I'd like to know what I'm sacrificing and what the impact on the beer will be.

Can anyone just cut to the chase and complete the following sentences:

Residual alkalinity is [not/somewhat/very] important. It should be the [first/second/third/last] thing you care about when setting your water profile, behind __________ and ahead of _______. If it is too low for your style, then _____; if it is too high for your style, then _____.
 
Wow, I am facing the exact same problem you are. I sort of posted it right before you did; you just did a better job of explaining it. When I get my PH of 5.55 I get a -75 RA. I can’t find any info on low RA. I’m starting to think it’s not a problem as long as your PH is good but who knows. I’ve been researching this for 2 days now and haven’t found one thing referring to this issue.
 
I recently tried to design a water profile for an oatmeal stout using a target profile from the Bru'n Water Calculator. It ended up saying that my mash pH was too high (~5.6) AND my RA was too low (~48).

I'm hoping that Bru'n Water isn't trying to guide you with a recommendation for RA. To my knowledge, there is nothing in the program that recommends a certain RA. Alkalinity and RA are the main factors that are contingent upon the actual grist used. Those water profiles in Bru'n Water include recommendations for bicarbonate content that are only first guesses. Since alkalinity and RA are directly a function of bicarbonate content, that means that they are first guesses too. The brewer will adjust bicarbonate content to better fit their actual grist acidity.

Forget about RA all together. The only thing that matters is the mash pH. RA is only a rough corollary for mash pH response and its clouded by too many other factors to be truly useful as a brewing parameter.
 
Residual alkalinity was cooked up by Paul Kolbach during WWII as a means of comparing brewing waters and for that it is quite useful. It's utility for this purpose is enhanced by plotting water characteristics on a chart like the one at http://www.pbase.com/agamid/image/57446374. Trying to hang too much significance on it is likely to lead one astray. Brewing water chemistry is intricate if not complex and many of us, home brewers that is, grasped at in desperation ascribing to it much more utility than it really has.
 
Interesting.

mabrungard & ajdelange: I certainly don't know enough to debate the matter with you, as I am just beginning the learning process. So I am just hoping for some clarification. The video I posted is certainly in the category of 'prompting a lot of utility' to the concept. Particularly at 24:25 he introduces an experiment he did with two beers, each brewed at two RA's. His conclusion was that the beers brewed at the right RA were complex, but the beers brewed at the wrong RA were one dimensional.

A pretty attractive result. I'd sure rather brew complex, multi-dimensional beers. So where am I not understanding him, or is he overstating something? Thanks,

Steve
 
Interesting.

Particularly at 24:25 he introduces an experiment he did with two beers, each brewed at two RA's. His conclusion was that the beers brewed at the right RA were complex, but the beers brewed at the wrong RA were one dimensional.

Oh, I agree with that result. The problem is with the connection to the 'right RA'. Its actually a connection to the proper mashing pH and RA is only a loose corollary to mash pH since the effect of the mash composition plays such a big part. Any connection between the appropriate RA and beer color is filled with problems.
 
Oh, I agree with that result. The problem is with the connection to the 'right RA'. Its actually a connection to the proper mashing pH and RA is only a loose corollary to mash pH since the effect of the mash composition plays such a big part. Any connection between the appropriate RA and beer color is filled with problems.

Okay, this will probably only muddy the waters. I am planning water adjustments in Bru'n Water for a Marzen I plan for this weekend.
Using the amber malty profile it suggests an RA of 45.
After some Gypsum and Calcium Chloride additions my estimated mash PH is 5.3 and the finished water profile shows an RA of -18.
If I add a little baking soda I get the RA to the 45 and my estimated mash PH is 5.6.
Heres the question, do I or don't I care what the RA is?
 
Not really. What you care about is that the mash (and subsequent) pH's are correct and that the calcium, chloride and sulfate levels are proper for the flavor/body profile you want.

As pointed out in #5 the value of RA is in its ability to roughly compare raw waters. If you look at the chart referenced in that post you will see what famous brewing cities have which RA's and, knowing the styles of beer brewed in those cities, have an idea as to what your water would be suited for without treatment under the presumption that 1. The chart is right about the cities' waters (it isn't in many cases) and 2. That the brewers brewed with the water for their cities without treatment (they didn't in many cases). Furthermore, you can get a rough idea as to what you must do, in terms of alkalinity reduction/increase or effective hardness reduction/increase or both to render your water like that of a particular city and this, presumably to make it more suitable for brewing the beer associated with that city. But, as noted above, it isn't enough to know what the water coming out of a Burton well is like to make good Burton style beers. You must know what the brewers of Burton,for example, did to it, if anything, to make the water they had more suitable for brewing (they decarbonated it by heating).

RA has a mathematical definition based on the alkalinity, calcium and magnesium content so it can be calculated whatever you do to the water as long as you know the alkalinity, calcium and magnesium. And this is what the spreadsheets do. But beyond comparing raw waters the RA doesn't really tell you much as the amount of acid contributed by calcium is, for reasonable amounts of calcium, small compared to the amount of acid you must typically add as acid malt, CRS, lactic acid, sauermalz etc.

John Palmer noted the correlation between beer styles' colors and the RAs of the raw waters that were associated with the breweries that produced them. The home brewing world assumed that this correlation was much tighter (higher r) than it really is and tried to make color a design parameter. I think enough water is over the dam, so to speak, at this point to have shown that this isn't a good approach and people are starting to back off on RA as the backbone of a beer design. But for seeing how your water compares to Dublin's an RA chart is still a useful tool. If you are mathematically inclined you can think of the RA chart as the projections of multidimensional water vectors onto a 2 dimensional space.

I should point out that at one time I too put a lot of weight on RA. Engineers are always looking for some figure of merit to hang their hats on and RA seemed to me, as it has to many others, to have lots of promise. And it is, of course, still valuable - just not as valuable as some formerly thought (and I guess still do).
 
Okay, this will probably only muddy the waters. I am planning water adjustments in Bru'n Water for a Marzen I plan for this weekend.
Using the amber malty profile it suggests an RA of 45.
After some Gypsum and Calcium Chloride additions my estimated mash PH is 5.3 and the finished water profile shows an RA of -18.
If I add a little baking soda I get the RA to the 45 and my estimated mash PH is 5.6.
Heres the question, do I or don't I care what the RA is?

No! RA is not a criterion for beer production. Only mash pH matters.

I uploaded a new version of Bru'n Water last week with revisions to the color-based water profiles that are stock in the program. Those profiles were created based on an assumption of creating a beer at the upper end of the color range. That produced estimates for a higher starting guess for the bicarbonate content for each profile. The revised profiles assume the production of a beer at the lower end of the color range and the starting guess for the bicarbonate content is much lower now. Correspondingly, the RA for those profiles is now lower too.

Since a lower than optimal mash pH range tends to make better beer than a higher than optimal mash pH range, this revision is less likely to lead a brewer astray. More importantly, a brewer should remember that their mash pH estimate is the primary goal and RA is not. Adjust the bicarbonate content of the mashing water to produce an acceptable mash pH.
 
No! RA is not a criterion for beer production. Only mash pH matters.

I uploaded a new version of Bru'n Water last week with revisions to the color-based water profiles that are stock in the program. Those profiles were created based on an assumption of creating a beer at the upper end of the color range. That produced estimates for a higher starting guess for the bicarbonate content for each profile. The revised profiles assume the production of a beer at the lower end of the color range and the starting guess for the bicarbonate content is much lower now. Correspondingly, the RA for those profiles is now lower too.

Since a lower than optimal mash pH range tends to make better beer than a higher than optimal mash pH range, this revision is less likely to lead a brewer astray. More importantly, a brewer should remember that their mash pH estimate is the primary goal and RA is not. Adjust the bicarbonate content of the mashing water to produce an acceptable mash pH.

Off topic here, Martin, but does the update include an option for pounds/ounces/gallons instead of liters/kilograms? My math skills stink, and I'm perpetually stuck in the US measurements.

One thing I've been happy with is concentrating on mash pH. Once in a while, I'm a little on the low end in a new batch, but overall I have been ignoring the RA and concentrating on a pH of 5.3-5.5 with good results.
 
Off topic here, Martin, but does the update include an option for pounds/ounces/gallons instead of liters/kilograms? My math skills stink, and I'm perpetually stuck in the US measurements.

One thing I've been happy with is concentrating on mash pH. Once in a while, I'm a little on the low end in a new batch, but overall I have been ignoring the RA and concentrating on a pH of 5.3-5.5 with good results.

What part of the spreadsheet are you talking about? Are you sure you didn't download the SI version as opposed to the US version?
 
No! RA is not a criterion for beer production. Only mash pH matters.

Thanks Martin. I just used version 1.13 to plan this weeks Marzen brew.
How do we reconcile the theory that RA is not important with Plamers video above? He suggests RA makes a difference in the complexity of the flavors.
 
RA is an important factor, but it is not more important than mash pH.

I appreciate John's sentiment regarding RA and getting the mash water RA in the proper range is important for getting the mash pH in range. But I have a disagreement that the finished beer color can be used to decide what that RA value should be. The grist composition can play havoc with the mash pH and that can throw that color-based RA correlation out of kilter. So, mash pH is actually the criterion that is more important to control.

Regarding complexity and RA. That can be a problem too. Look at 2 water profiles (Pilsen and Burton) that have nearly identical RA values (around zero) and it should be no problem to see that these waters would impart totally different character to beer. So, that argument can be subverted.

On the other hand, I have experienced beers that were brewed with RA levels that did not produce appropriate mash and kettle pH. Their 'complexity' (taste quality) was lacking in comparison to beers brewed with appropriate water. At a general level, RA is important. It's just that it is not THE thing that the brewer should use to assess if their water is suitable.
 
John is still a little hung up on RA but I think he is coming around. I'm actually starting to feel a little vindicated in all this.

If you desperately need something to hang onto in this turbulent sea of brewing water chemisty, and we do, you are likely to grasp at anything that floats. RA/SRM and Cl/SO4 are a couple of things that have been tried. What happens is that a correlation is observed. In particular here presumably John brewed a couple of beers and found a relationship between something he likes and RA. Let's say I brew a bunch of stouts and adjust the RA's and submit the beers to a competition and receive a set of scores like those shown in this picture:
https://www.homebrewtalk.com/photo/false-correlation-56032.html

You have to click on it to see the details. In any event these data show that clearly increasing RA increases one's score. I did not brew these beers this is synthetic data for illustration purposes. The scores and RA are, in this picture, completely independent random variables. There is no correlation between them (even though Pearson's r for this set is fairly high). Were I to take enough data from this model the lack of correlation would become apparent. The point is that random chance can make things appear to be correlated when in fact they are not and I suspect that may be what is responsible for John's comment (though to be honest I haven't listened to the talk).

Another thing that bites people is confusion of correlation with causation. It was observed, for example, that when the US lowered its speed limit to 55 during a fuel crisis highway deaths went down substantially and it was assumed, quite reasonably, that lowering the speed limit lead to safer driving. But traffic deaths also went down in Germany where they didn't lower their speed limits. Lower deaths and lower speed were correlated but the causative factor was that there were fewer people driving because fuel was in short supply. In the brewing context if one adds more and more calcium chloride to his beers they are likely to taste better (up to a point) because of the chloride's sweetening and smoothing effects. But RA is also going down as calcium chloride additions are being increased. So RA and beer quality are correlated but it is in fact the increased chloride that is responsible. Again I'm not suggesting that this is the actual explanation for John's comments but just pointing out there are several ways in which he could have been lead to his conclusion.

Then there is our ancient foe cognitive bias. Once you (or anyone) decides on something he tends to clearly see and remember anything that supports his belief in this something and not notice nor long remember anything that contradicts it. This has not only ruined a lot of beer but destroyed a lot of investors' portfolios and caused plenty of misery in general.
 
I'm going to resurrect this thread because I just learned something that cleared the whole thing up for me, so I thought I'd post here in case the same thing can occur for others.

I was reading a thread on water pH on the AHA website, got confused, so asked this question:
"Oh my. There is so much I don't know. This statement at my current level of understanding makes no sense. Alkalinity is just one side of the sliding scale we call pH, isn't it? Alkalinity is just the opposite of acidic on this scale isnt it?"

To which I got a couple of great responses: first from NATEO:
"Think of alkalinity as the water's resistance to acidification. Think of the pH spectrum as acidic to basic. Alkalinity represents the water's ability to neutralize an acid, and has no direct impact on pH.

My water, for instance, has insanely high alkalinity but typically has a pH of 7.4. Since it has a lot of alkalinity, it takes a lot of acid to move the pH downward, as the alkalinity is "consumed" by the acid. Once the acid eats all the alkalinity, there is nothing in the water to stop the acid, and so any more acid drops the pH by a lot."


Then MABRUNGARD added to this by saying:
"There is a definition of alkalinity that presents it as the opposite of acidity. Unfortunately, that is not the definition in use here. Alkalinity is a measure of the buffering capacity of the liquid or resistance to acidification as Nate mentions. In typical drinking water, alkalinity is the measure of carbonate and bicarbonate ions in the water. They are the ions primarily responsible for alkalinity. Therefore, alkalinity is not equivalent to pH. They can be quite different."

That obviously changes my whole understanding of what Residual Alkalinity means. I love epiphanies like this!
 
To continue, I was getting frustrated chasing my tail trying to get the RA to be anywhere in the ballpark of where it was supposed to be. I finally gave up and just followed MABRUNGARD's advice and just attended to mash pH.

The big part of the problem was that I use RO water, in which there is presumably NO RA - no buffering capacity. So to get the RA where "it should be" meant that I had to raise the pH to where it shouldn't be.

I am certain I still have something incorrect in my mental map of all this, but I'm pretty certain a big foundation stone was just put in place.

Steve
 
I'm not sure about that. I've never found RA to be a good indicator. It was always frustrating to try and get the RA where it needed to be with my water. Way too much alkalinity.

I just focus on pH and try to get the various minerals to their recommended ranges for yeast health and flavor. The chloride:sulfate ratio helps me choose which minerals to add to raise or lower pH and target a balanced flavor. I'm not convinced I've found that the chloride:sulfate ratio is all that important if you get a mix of minerals that promote yeast health and target a good pH.
 
I wonder if part of it is because the allure of the term RA is "sexier" than the term "mash pH."

This hobby is full of those terms: strike water, dough-in, dry hop, vorlauf, etc.
 
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