Calculating Water PH after Gypsum not Mash PH - Home Brew Forums

Register Now!
Home Brew Forums > Home Brewing Beer > Brew Science > Calculating Water PH after Gypsum not Mash PH

Reply
 
Thread Tools
Old 05-30-2012, 05:31 PM   #1
BrewThruYou
Recipes 
 
Sep 2010
Ambler
Posts: 1,689
Liked 41 Times on 38 Posts



Just a quick question hopefully. I'm using Bru'n Water and love it.

My water is high in bicarbonates and low in sulfates. For hoppy pale beers, I usually treat my tap water by diluting it 50% with distilled and then adding back gypsum. I usually treat the brewing water all at once except for sparge acidification. For this particular beer, I'm adding 1.3g of gypsum per gallon.

Using the sparge acidification tab of Bru'n water, I've also been using 10% phosphoric acid to lower the sparge water PH. The sparge acidification tab lists the starting water PH...per my water report, it's 6.9. However, didn't I already lower the water PH with the gypsum additions? If so, how do I calculate the the new liquor PH so I can recalculate the sparge acid addition?

Thanks!

 
Reply With Quote
Old 05-30-2012, 06:58 PM   #2
ajdelange
HBT_LIFETIMESUPPORTER.png
Recipes 
 
Aug 2010
McLean/Ogden, Virginia/Quebec
Posts: 9,042
Liked 1403 Times on 1070 Posts


Gypsum (calcium sulfate) is the salt of a strong acid (sulfuric acid) and a strong base (calcium hydroxide). Therefore, it does not have an appreciable effect on the pH of solutions to which it is added. There are, of course, exceptions. And one of those is when it is added to a solution which contains a sufficient amount of phosphate at high enough pH that sufficient phosphate is in the tribasic form in which case calcium will coalesce with it precipitating as apatite. The loss of tribasic phosphate causes dibasic to convert to tribasic to try to re-establish equilibrium as well as the conversion of monobasic to dibasic to make up for the loss of dibasic and of the acid to monobasic to make up for the loss of monobasic. Each of these results in the release of hydrogen ions which lower the mash pH. This is why calcium is often supplemented in brewing. It lowers mash pH by reacting with the phosphate in the malt.

 
Reply With Quote
Old 05-30-2012, 07:08 PM   #3
mabrungard
HBT_LIFETIMESUPPORTER.png
 
mabrungard's Avatar
Recipes 
 
Feb 2011
Carmel, IN
Posts: 4,116
Liked 600 Times on 464 Posts


Gypsum doesn't lower water pH by itself. Its only when combined with malt in the mash that there is an acid-producing reaction that creates a pH reduction. Sparge water pH (alkalinity really) must be reduced via an acid addition.
__________________
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 05-30-2012, 07:48 PM   #4
BrewThruYou
Recipes 
 
Sep 2010
Ambler
Posts: 1,689
Liked 41 Times on 38 Posts


Thanks guys. You two are the best. I'll continue using 6.9 as the water input when acidifying the sparge water with phosphoric acid.

 
Reply With Quote
Old 05-31-2012, 05:05 AM   #5
tgmartin000
Recipes 
 
May 2011
Denver, CO
Posts: 1,255
Liked 87 Times on 72 Posts


If I may, another question.

If I use all RO for my sparge, will the pH of the sparge rise? Assuming my mash pH is 5.4,will that go up?

 
Reply With Quote
Old 05-31-2012, 05:05 AM   #6
tgmartin000
Recipes 
 
May 2011
Denver, CO
Posts: 1,255
Liked 87 Times on 72 Posts


If I may, another question.

If I use all RO for my sparge, will the pH of the sparge rise? Assuming my mash pH is 5.4,will that go up?

 
Reply With Quote
Old 05-31-2012, 10:05 AM   #7
mabrungard
HBT_LIFETIMESUPPORTER.png
 
mabrungard's Avatar
Recipes 
 
Feb 2011
Carmel, IN
Posts: 4,116
Liked 600 Times on 464 Posts


In my experience, RO water for sparging does not require any pH (or alkalinity) adjustment since its alkalinity is already very low. It is not likely to exhaust the acidity of the mash which would lead to a rise in pH rise and all the bad things that may result from that rise.
__________________
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
Reply
Thread Tools


Similar Threads
Thread Thread Starter Forum Replies Last Post
Gypsum bosox Brew Science 11 01-15-2013 03:43 PM
Adding Gypsum - Water Report Calculations Grinder12000 Brew Science 24 04-23-2012 01:16 PM
Gypsum NOT dissolved ! hector Brew Science 13 01-08-2012 12:30 AM
Calculating strike water temp - HELP promontory Brew Science 6 02-17-2011 04:18 PM


Forum Jump