Bicarbonate from Total Alkalinity - Home Brew Forums
Home Brew Forums > Home Brewing Beer > Brew Science > Bicarbonate from Total Alkalinity

Reply
 
Thread Tools
Old 12-05-2012, 04:05 PM   #1
TrexAssmaster
Recipes 
 
Sep 2010
Lansing, MI
Posts: 6



I am really hoping someone can help me with this! I am entering my local water profile into Beersmith and I am missing a few fields. I had my water tested at a local, professional, lab and have the water report. I have data for Total Alkalinity and pH, as well as hardness, chloride, SO4, calcium, and Sodium. There was no data for magnesium. My question is, how do I properly calculate bicarbonate from the parameters I have? I have looked on several forums and seem to get different answers every where I look. Any and all help on this issue is greatly appreciated!

 
Reply With Quote
Old 12-05-2012, 04:41 PM   #2
bdh
Recipes 
 
Feb 2012
Baltimore, MD
Posts: 171
Liked 19 Times on 9 Posts


From what I understand, unless the pH of you water is extremely high (above 8.5 or so) then you can assume almost all of the total alkalinity is in the form of bicarbonate. Note that if alkalinity is reported as CaCO3 then you need to multiply that number by 1.22 to get the bicarbonate concentration.

You can also calculate the magnesium concentration if you want using the equation:

Hardness as CaCO3 = 2.5[Ca2+] + 4.1[Mg2+]

TrexAssmaster Likes This 
Reply With Quote
Old 12-05-2012, 05:23 PM   #3
TrexAssmaster
Recipes 
 
Sep 2010
Lansing, MI
Posts: 6


Thanks for the reply! The pH here is 8.71. The total alkalinity is reported as 185 mg/L but it isn't specified if that is CaCO3, but I am assuming it is. The same goes for hardness, they did not specify on many of the parameters, but again, I will assume hardness as CaCO3. Thanks again for your help!

 
Reply With Quote
Old 12-05-2012, 05:44 PM   #4
bdh
Recipes 
 
Feb 2012
Baltimore, MD
Posts: 171
Liked 19 Times on 9 Posts


Well at that pH you'll start getting some carbonate in addition to bicarbonate (but it will still be largely bicarbonate). I'd recommend downloading a copy of Bru'n Water (https://sites.google.com/site/brunwater/). It has a calculator there that will give you the carbonate/bicarbonate concentrations given the pH and alkalinity (and calculate most everything else you'll need to calculate for your water).

That's a fairly high alkalinity which will need to be reduced for most beer styles. If you post the full water profile I'm sure someone will chime in with more specific advice about what to do with the water.

TrexAssmaster Likes This 
Reply With Quote
Old 12-05-2012, 06:01 PM   #5
HopSong
Senior Member
HBT_LIFETIMESUPPORTER.png
 
HopSong's Avatar
Recipes 
 
Sep 2011
Santa Rosa, CA
Posts: 1,950
Liked 101 Times on 89 Posts


Does your city publish a water report? Check it out on line or call them. They are required to check for certain things. I think Mg is one.
__________________
Cheers, Bill
Hop Song Brewing

 
Reply With Quote
Old 12-05-2012, 06:05 PM   #6
TrexAssmaster
Recipes 
 
Sep 2010
Lansing, MI
Posts: 6


Thanks again bdh. HbgBill, they do but it only includes data for contaminants and additives, such as chlorine.

 
Reply With Quote
Old 12-05-2012, 08:15 PM   #7
mabrungard
HBT_LIFETIMESUPPORTER.png
 
mabrungard's Avatar
Recipes 
 
Feb 2011
Carmel, IN
Posts: 4,111
Liked 596 Times on 461 Posts


As bdh said, there is a conversion calculator on the Water Report Input page of Bru'n Water. That will provide the values you need for your other program. Since the pH is a little high, there will be a little CO3 along with the HCO3. I would just plug in the reported alkalinity and a lower water pH that will give you the result as virtually all HCO3. That can then go into any water program.
__________________
Martin B
Carmel, IN
BJCP National
Foam Blowers of Indiana (FBI)

Brewing Water Information at:
https://sites.google.com/site/brunwater/

Like Bru'n Water on Facebook for occasional discussions on brewing water and Bru'n Water
https://www.facebook.com/pages/Brun-...?ref=bookmarks

 
Reply With Quote
Old 12-06-2012, 01:49 PM   #8
ajdelange
HBT_LIFETIMESUPPORTER.png
Recipes 
 
Aug 2010
McLean/Ogden, Virginia/Quebec
Posts: 9,019
Liked 1400 Times on 1067 Posts


If you copy this

((((((-0.0591384*pH + 3.11647)*pH - 70.2631)*pH + 878.007)*pH - 6565.02)*pH + 29368.026)*pH - 72780.088)*pH + 77220.723

into a spreadsheet cell and replace 'pH' with the name of a cell which contains a pH value between 5 and 9.5 (or declare a variable named 'pH') the cell containing this polynomial will evaluate to the number of mg/L bicarbonate for a solution of alkalinity 100 ppm as CaCO3 (titrated to end point 4.3). The attached graph shows calculated values, the polynomial fit to them and the residuals. It also clearly shows the 'flat' region (between, say, pH 6 and 8.3) where 61*alk/50 is reasonably accurate.
Click image for larger version

Name:	bicarbAlk.jpg
Views:	3205
Size:	50.9 KB
ID:	87158  

 
Reply With Quote
Old 12-11-2012, 06:57 PM   #9
Kaiser
 
Kaiser's Avatar
Recipes 
 
Nov 2005
Pepperell, MA
Posts: 3,895
Liked 127 Times on 73 Posts


A.J's reply is correct. But in the context of brewing water calculators you need to know that most of them ask for bicarbonate to calculate alkalinity. And since most of them are using the simple "alkalinity = bicarb * 50 /61" formula you should calculate bicarbonate as "alkalinity * 61/50" when your water calculator asks for bicarbonate. To be correct, water calculators should ask for alkalinity *or* bicarbonate and pH.

Kai

 
Reply With Quote
Old 12-12-2012, 07:55 PM   #10
TrexAssmaster
Recipes 
 
Sep 2010
Lansing, MI
Posts: 6


Thanks a bunch everyone, you all helped me out tremendously!

 
Reply With Quote


Reply
Thread Tools


Similar Threads
Thread Thread Starter Forum Replies Last Post
Total alkalinity question oldbullgoose All Grain & Partial Mash Brewing 8 09-25-2012 04:03 PM
Total Alkalinity, CaCO3 as a function of Bicarbonate, HCO3 jmf143 Brew Science 13 02-14-2012 02:22 PM
Alkalinity as CaCO3 and Bicarbonate bbeckett Brew Science 4 02-24-2011 03:56 PM
Clarifying my Bicarbonate/Alkalinity for Beersmith EuBrew Brew Science 4 12-31-2010 04:31 PM
Water Questions: (Maxes for) Residual Alkalinity, Bicarbonate, Calcium Hop Brew Science 4 03-02-2010 02:38 PM


Forum Jump