My German water report.

Hello,

I am looking for help for translating this german water report for input into Bru'n Water. I've been working this thing for quite some time and cant get the numbers to balance. I realize it is missing Bicarbonate and Alkalinity but i am wondering if it is still workable? Braukaiser has a tool for finding the missing number. However, my brain and eyes are bleeding and i have to reach out to you guys. I am using the SI version of Bra'n Water.

Thanks


pH-Wert 7,8
Calcium 68.6 mg/l
mg 24.7 mg/l
Hardness 15.3 DH
NA 13mg/l
K 4.5mg/l
FE <0.01mg/l
NO3 17.4mg/l
Chlorid 24.1 mg/l
Sulfat (SO4)2 - 41.6mg/l
F .37mg/l
Pesticides - Nicht
Sauerstoffgelost (o2) 9.5 mg/l
Uran .0013
Leitfähigkeit bei 25° C 581 µS/cm

Water report : http://www.fwf-uffenheim.de/index2.php/fwf/C103?mgd=100&vb=versorgungsbereich6&teil=Colmberg

BrauKaiser that i am citing:
http://braukaiser.com/wiki/index.ph..._if_alkalinity_and_bicarbonate_are_missing.3F

It appears that the bicarbonate content is likely to be in the 265 ppm range. That produces a fairly high alkalinity. That factor and the somewhat elevated Mg suggests that some dilution along with some acidification would be needed for that water.

What did you use to estimate the bicarbonate? And also, thank you.

As stated at Kai's site, the general idea is to stuff in bicarbonate ion until cation charge and anion charge balance. The only problem with doing that is that when you stick in bicarbonate some of it converts to carbonate and that alters the charge further. This is generally not a problem at lower pH but as pH appraoches 8 and goes over it does become a factor. Thus the proper thing to do is stuff in carbo which can exist in three forms, carbonic acid with no charge, bicarbonate with -1 charge and carbonate with -2, use the pH to figure out how the carbon will distribute itself among these three moieties and calculate the charge, adjusting the carbo until you get balance. Doing this for your water report results in an alkalinity (assuming end point pH for the titration of 4.5) of 3.88 mEq/L (194 mg/L as CaCO3) and bicarbonate content of 236.5 mg/L.

The accuracy of this estimate depends on the accuracy of all the other measurements and assumes they were made on the same sample of water. If calcium content was measured on Tuesday and sulfate on Thursday you must add temporal variation to the uncertainty. It also assumes that ions not measured (potassium, phosphate, strontium...) are present in only small quantities. In other words, don't count on the 236.5 number being very accurate.

AJ, thanks for your input. You brought up some very good points and I'm back to the books to read more. Brungards number balances BRU'N, however you seemed to have included some variables that the program (and my report) don't address. I think i have a great starting point. Ultimately, it all comes down to the "does this taste good" test anyway. Thanks again

In my spreadsheet I generally don&#8217;t care about the distinction between bicarbonate and carbonate. I&#8217;m aware of this imprecision, but this keeps things simple. Just like pH of the water it doesn't matter much since in the end it&#8217;s all converted to alkalinity anyway.

if your balance is missing 50 mEq/l anions, then you can add

50 mEq/l bicarbonate
40 mEq/l bicarbonate and 10 mEq/l carbonate
or 50 mEq/l carbonate

In the end you&#8217;ll always end with about 50 mEq/l alkalinity. I say about b/c there is also some alkalinity associated with changing the pH. But that alkalinity is small compared to the level of alkalinity that generally comes from the carbo ions.

I do agree however, that if the imbalance is caused by more than missing bicarbonate/carbonate you will not be able to deduct the alkalinity in this way.

It&#8217;s odd that the alkalinity (Saeurekapazitaet) is missing from this report. It&#8217;s a detailed enough report that it should be listed. On the other hand, it&#8217;s mostly us brewers who care about this.

Kai

Thanks Kai, I'm digging through you links now.

I agree with Kai, the distinction with regard to bicarbonate and carbonate distribution is typically minor in many waters and assuming that the predominant form is bicarbonate is usually close enough.

Gee I don't know about that. Depends on pH. I guess my feeling is that as it isn't very difficult to calculate the relative amounts you might as well do it right. Here's how - not that anyone will really want to do it but just to show how simple it is

r1 = 10^(pH - 6.38)
r2 = 10^(pH - 10.38)
f1 = 1/(1 + r1 + r1*r2)
f2 = r1*f1
f3 = r2*f2

f1, f2 and f3 are the fractions of carbon atoms in, respectively, carbonic acid, bicarbonate ion and carbonate ion. Thus if Ct is the total number of carbon atoms f1*Ct are in carbonic, f2*Ct are in bicarbonate and f3*Ct in carbonate. To calculate the amount of bicarbonate from the alkalinity convert to mEq/L then mEq/L = Ct*(f1e - f1s) + Ct*(f3s - f3e) + (H+ required to shift pH of water from pHs to pHe) where s designates the sample pH and e the end point pH. Solve for Ct then Ct*f2 is the bicarb.

The graph below shows estimated bicarbonate content from:
1. The commonly used approximation 61*Alkalinity/50
2. Use of f1, f2 and f3 under the assumption that the alkalinity titration end point was 4.5
3.Use of f1, f2 and f3 under the assumption that the alkalinity titration end point was 4.3.

It is apparent that the titration end point pH has a large influence on the size of the error. I suppose you can argue that as you don't usually know what that pH is the approximation is justified.