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Old 06-15-2012, 01:40 PM   #1
Sep 2011
Robbinsdale, MN
Posts: 796
Liked 77 Times on 64 Posts


I brewed a tripel recently with 100% RO have noticed that Castle pilsner may have a lower pH in distilled water than other pilsner malt. I did a test mash and determined I needed less acid than predicted to achieve an actual mash pH >5.3 at room temperature.

I want to brew a Dark Strong with >65% Castle pilsner and other darker grains and did a test mash last night while brewing another beer because I suspected that combination may result in a pH <5.3 without any acid and 100% RO water. That indeed was the case and was able to fine-tune the pH prediction based on the test to develope a plan to brew this. I can either use 25% of my water as tap water [350 ppm alkaline (CaCO3)] and no acid or use 100% RO with slaked lime.


I generally treat all my water for brewing the same but never used a base before. With bases, would you add them to the mash only? If I mixed water, would I mix tap water in for the mash only and use 100% RO water for sparging? I batch sparge.

I've only brewed ligher colored beer ever since starting 100% RO and have never saw the pH go lower than could be corrected by using less acid malt.

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Old 06-15-2012, 03:39 PM   #2
mabrungard's Avatar
Feb 2011
Carmel, IN
Posts: 4,163
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Yes when your water has too little alkalinity, adding a base or basic buffer may be necessary for mashing water. But, its never 'needed' in sparging water. Low alkalinity is a desirable trait in sparging water under all circumstances.
Martin B
Carmel, IN
BJCP National
Foam Blowers of Indiana (FBI)

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