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-   -   Just how much does Residual Alkalinity matter. (http://www.homebrewtalk.com/f128/just-how-much-does-residual-alkalinity-matter-310776/)

Pugs13 03-06-2012 07:13 PM

Just how much does Residual Alkalinity matter.
 
I was just wondering your thoughts on residual alkalinity. I am brewing a stout and have these numbers figured for my pH. I have hear both that residual alkalinity matters and have also heard don't listen to anything pertaining to RA when pertaining to color or SRM. Can you guys give me some insight. Here are the numbers I have figured for our stout. The pH may be in check but the RA is obviously off if you are pertaining to color. Let me know your thoughts.

Starting Water (ppm):
Ca: 78
Mg: 27
Na: 10
Cl: 2
SO4: 15
CaCO3: 328

Mash / Sparge Vol (gal): 4 / 3.5
RO or distilled %: 80% / 0%

Total Grain (lb): 8.9

Adjustments (grams) Mash / Boil Kettle:
CaSO4: 2 / 0.75
CaCl2: 2 / 0.75
MgSO4: 0 / 0
NaHCO3: 0 / 0
CaCO3: 0 / 0
Lactic Acid (ml): 0
Sauermalz (oz): 0

Mash Water / Total water (ppm):
Ca: 82 / 93
Mg: 5 / 15
Na: 2 / 6
Cl: 64 / 48
SO4: 77 / 63
Cl to SO4 Ratio: 0.84 / 0.76

Alkalinity (CaCO3): 66
RA: 4
Estimated pH: 5.55
(room temp)

ajdelange 03-06-2012 08:15 PM

If you brew a typical Irish stout with base malt, 10% roast barley, approximately an equal amount of flaked barley and use very soft (RO or DI) water with an RA about 0 you will get a mash pH of about 5.5. This is OK but perhaps a little on the high side. Your water has an RA of 256. That's too much for any beer including a stout. Using Kohlbach's rule of thumb your mash pH would be about 0.43 pH higher than the DI water pH or 5.9. That is definitely too high. You will get beer and it might even be fairly good but it will certainly not be as good as it could be if the mash pH were more like 5.4.

There are spreadsheets out there that will try to tell you that if the beer is 60 SRM you need an RA of 350. This is nonsense. Most of those spreadsheets have been modified or at least caveated to the point where such ridiculous conclusions are not so likely to be drawn. The color SRM tie in was based on correlation of beer color (as calculated by a model based on the style guidelines) and the alkalinity of the water with which it was supposed that these beers were brewed. A correlation analysis was done and a trend noted but no one looked at Pearson's r. This is a statisticians way of saying that while in broad terms the RA of the water that is used to brew beer of a certain color may be higher than that of the water used to brew a lighter beer, the range of RA for any particular color can be vast. RA and color are much too weakly correlated to allow one to be used as a predictor of the other.

Your best bet for brewing a stout with the water you have is to do exactly what you propose to do: dilute it way down with RO, supplement the Calcium and brew!

Pugs13 03-06-2012 09:55 PM

Your best bet for brewing a stout with the water you have is to do exactly what you propose to do: dilute it way down with RO, supplement the Calcium and brew![/QUOTE]

I was able to change up the grain bill a little to bring down the pH to 5.4 by utilizing some darker malts. I also took into consideration that I will be doughing in with 1.5qt./lbs. of grain. This is only 3.21 gallons of water. Thus, I will only be using about 1/2 gallon of the water and then that will be diluted 85% with distilled water. I guess what is confusing me is this "Effective Alkalinity" which is now at 49. What is a reasonable number here for an Irish Stout, does this even matter if you have your pH balanced to where it should be?

Pugs13 03-06-2012 09:59 PM

Maybe I am just reading too much into this water chemistry stuff and I should just brew the damn beer!

ajdelange 03-06-2012 11:02 PM

Certainly a lot of time and effort has been wasted by home brewers trying to over engineer their water (and I was certainly one of them). You can make fine beer by starting out with the guidelines set out in the Primer and then adjusting from there and that seems to be the direction in which experienced brewers are moving i.e tune for good beer - not a particular water ion profile. It is still necessary to broadly follow style guidelines (e.g. you wouldn't try to brew a Boh. Pils with high sulfate water) but the taste of the beer should be the criterion that drives the process.

I don't know what 'effective alkalinity' is. My guess would be that it is the alkalinity of water diluted n:1 and is, thus the alkalinity of the original water divided by (n+1).

Pugs13 03-06-2012 11:29 PM

Quote:

Originally Posted by ajdelange (Post 3865343)
Certainly a lot of time and effort has been wasted by home brewers trying to over engineer their water (and I was certainly one of them). You can make fine beer by starting out with the guidelines set out in the Primer and then adjusting from there and that seems to be the direction in which experienced brewers are moving i.e tune for good beer - not a particular water ion profile. It is still necessary to broadly follow style guidelines (e.g. you wouldn't try to brew a Boh. Pils with high sulfate water) but the taste of the beer should be the criterion that drives the process.

I don't know what 'effective alkalinity' is. My guess would be that it is the alkalinity of water diluted n:1 and is, thus the alkalinity of the original water divided by (n+1).

Yeah I do not know either. All I know is that my pH is now down to 5.4 with an RA of 1. At this point I do not really care anymore. I am just going to go with this and brew some damn beer. The truth that I may have to stomach is that this idea of using this water as a marketing plus for future endeavors may just not be worth it. I mean right now I am only using about 1/2g. of it anyways. Is that really worth it? Something I will have to determine after this batch. My chloride to sulfate ratio states balanced with being just above .77. Everything else looks good so I am just going to go with it.

ajdelange 03-07-2012 12:38 PM

Quote:

Originally Posted by ajdelange (Post 3865343)
I don't know what 'effective alkalinity' is. My guess would be that it is the alkalinity of water diluted n:1 and is, thus the alkalinity of the original water divided by (n+1).

No, that's not it. Someone posted a EZ spreadsheet and I had a look at that. Effective alkalinity is apparently the alkalinity after acid has been added. If water has an alkalinity of 100 that means it takes 2 mEq of acid to lower the pH of a liter of it to 4.3. So if, for example, you add a total of 4 mEq/L to water with alkalinity 100 i.e. enough to get to pH 4.3 and then an additional 2 mEq of acid per L the pH will go even lower and the alkalinity would be -100.

Homercidal 03-07-2012 02:07 PM

I suggest that you not postpone a brew just because you are still struggling with your water.

However, I do think that you should continue to read up on articles, and listen to podcasts about water chemistry. It's not that difficult once you reach that aha moment. However, your water is pretty bad.


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