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Brews & Views Bulletin Board Service * Brews and Views Archive 2009 * Archive through March 01, 2009 * Low mash pH < Previous Next >

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Jeff Dieterle
Junior Member
Username: Dietejr

Post Number: 46
Registered: 03-2004
Posted From: 72.171.0.146
Posted on Saturday, February 07, 2009 - 05:42 pm:   Edit Post Delete Post View Post/Check IP    Ban Poster IP (Moderator/Admin only)

Since I started using RO water my mash pH has been around 5.0(measured cold and low srm beers). My efficiency has been normal and beer color is on target. My RO water report stated the pH at 7.3, however I get a 5.5 pH at the tap so I don't get the discrepancy, unless it has something to do with the several year old Colorphast strips I'm using. I realize the pH will drop as RO water sits because it absorbs CO2, which is my case because I only collect about a gallon/hour. I'm reluctant to add chalk or baking soda because the alkalinity of my RO water is 113 and I don't want to increase it for low srm beers.
Checking in to see if anybody else has experienced this with Ro water and any other thoughts on my low mash pH.
 

Bill Pierce
Moderator
Username: Billpierce

Post Number: 9927
Registered: 01-2002
Posted From: 24.150.192.193
Posted on Saturday, February 07, 2009 - 07:42 pm:   Edit Post Delete Post View Post/Check IP    Ban Poster IP (Moderator/Admin only)

In general I don't recommend using 100 percent RO-filtered water for all-grain beers unless some calcium is added. Also, an alkalinity of 113 mg/L as CaCO3 seems high for RO filtration, unless the unfiltered water is tremendously alkaline or the filter needs maintenance. At any rate, distilled or RO-filtered water has very little buffering ability, so pH readings of the water itself are notoriously variable.

I have trouble believing that water with an alkalinity of 113 mg/L as CaCO3 would show a mash pH of 5.0. Yes, it's possible your strips are too old, especially if they have been stored in a humid environment.
 

Jeff Dieterle
Junior Member
Username: Dietejr

Post Number: 47
Registered: 03-2004
Posted From: 72.171.0.146
Posted on Saturday, February 07, 2009 - 09:01 pm:   Edit Post Delete Post View Post/Check IP    Ban Poster IP (Moderator/Admin only)

I was surprised when I got the report regarding the RO water alkalinity also. The RO unit has only processed around 75 gallons of water. My hard water alkalinity is 350ppm, the bicarbonate is 426ppm. Also the chemistry most likely fluctuates because the aquafer we pump from can only supply 1-2gpm so we have to be careful or we'll run it dry.
I'll try some new strips. When I mix the RO water with my well water, are the ratios of Ca & Mg in the same proportions as the volume ratio of the two waters?
 

Bill Pierce
Moderator
Username: Billpierce

Post Number: 9929
Registered: 01-2002
Posted From: 24.150.192.193
Posted on Sunday, February 08, 2009 - 12:31 am:   Edit Post Delete Post View Post/Check IP    Ban Poster IP (Moderator/Admin only)

I agree about measuring the mash pH with fresh strips.

I am under the impression that DO filters should remove 85-95 percent of dissolved minerals.

Yes, you can assume that the minerals remain in proportion to the ratio of the water that is mixed. There are no doubt some ionic interactions that change the numbers slightly, but I doubt they are significant enough to make a major difference.
 

michael atkins
Advanced Member
Username: Mga

Post Number: 701
Registered: 11-2003
Posted From: 209.181.157.99
Posted on Sunday, February 08, 2009 - 01:25 am:   Edit Post Delete Post View Post/Check IP    Ban Poster IP (Moderator/Admin only)

FWIW - Per Ward Labs my Pre and Post RO water tests are:

Well water (Pre RO) ca 62, Mg 13, and HCO3 268 very alkaline.

Post RO is Ca 4, Mg 0, HCO3 40.

I always add calcium chloride and/or Gypsum for my lighter beers.

This would support the 85% comment by Bill P.
 

Jeff Dieterle
Junior Member
Username: Dietejr

Post Number: 48
Registered: 03-2004
Posted From: 72.171.0.146
Posted on Sunday, February 08, 2009 - 02:26 pm:   Edit Post Delete Post View Post/Check IP    Ban Poster IP (Moderator/Admin only)

Michael, your results are more what I hoped for. My Ca and Mg dropped from 110 & 30 to 11 and 5 respectively, but the bicarbonate drop was only around 65%.
 

Jeff Dieterle
Junior Member
Username: Dietejr

Post Number: 49
Registered: 03-2004
Posted From: 67.142.130.42
Posted on Tuesday, February 10, 2009 - 02:41 pm:   Edit Post Delete Post View Post/Check IP    Ban Poster IP (Moderator/Admin only)

The best guess I have on the high alkalinity is my well water alkalinity is so high to begin with and RO filtration does nothing to dissolved gases, particularly Co2.
So far I've only used my RO water twice, A Kolsch that is lagering now which I did increase the Ca to an acceptable level along with a few other salts for flavor. The other batch was for canned starter wort and I left the RO water pristine, so I'll see how it goes when I step-up and ferment.
Following my other question about minerals and water proportion, is it a reasonable assumption that the alkalinity will also remain in proportion to the blended waters like the minerals?
 

Bill Pierce
Moderator
Username: Billpierce

Post Number: 9938
Registered: 01-2002
Posted From: 24.150.192.193
Posted on Tuesday, February 10, 2009 - 03:22 pm:   Edit Post Delete Post View Post/Check IP    Ban Poster IP (Moderator/Admin only)

Jeff, the answer is yes, because the alkalinity is a function of the carbonate/bicarbonate/carbonic levels. At the pH of most water (below 8.4), this is primarily in the form of bicarbonate ions.

I hate to sound like a broken record, but the chapter on mash water chemistry in Palmer remains the best treatment of the subject.
 

Jeff Dieterle
Junior Member
Username: Dietejr

Post Number: 50
Registered: 03-2004
Posted From: 67.142.130.42
Posted on Tuesday, February 10, 2009 - 05:35 pm:   Edit Post Delete Post View Post/Check IP    Ban Poster IP (Moderator/Admin only)

Thanks Bill, ya I wish I had a nickle for everytime I referred to Palmers book, if it only would stick.