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Old 10-25-2009, 03:32 PM   #1
natalukas
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Okay, there's a lot to this so bare with me:

My water profile here is a bit high (6.2 pH according what the city posted a year or 2 ago) so I have to adjust for that. Usually I look at what percentage crystal/roast malts I have and then subtract (-0.3 for 10%, -0.5 for 20%) If I still need to drop I use acidulated malt (1% of grain bill will drop the pH by 0.1). In my mash yesterday I decided to use a 1/4 tablet of campden (potassium metabisulphite) for every 5 gallons water. When I checked my pH I was down to 5.0 which is lower than I expected. Another factor to consider is I used Munich 15 as 23% of my grain bill.

Was this due to the campden tablets? Does Munich malt effect the pH? or do you think it might some other factor that I haven't even considered?


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Old 10-25-2009, 05:37 PM   #2
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Your water's pH has nothing to do with what your mash pH is going to be unless you know the rest of the ionic content.


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Old 10-25-2009, 06:18 PM   #3
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Bobby- That seems odd, since in the past, using the crystal/roast deductions and the acidulated calculations, it has worked perfectly. (i.e. I have been able to control my mash pH starting with the water calculations and doing the deductions as noted) As far as I know the water pH is calculated from the ionic content, otherwise you wouldn't know it's pH (isn't that what pH is after, a calculation of a substance's acidity based on it's ionic content? Please correct me if I'm wrong.)

Another factor I just realized I forgot to mention is that I added 1/2 # oats to the recipe, I guess that might acount for the additional drop in pH, eh?

Really I wasn't that far under my target, and conversion went well (I hit my OG target of 1.054) I am just looking to understand pH in the mash a bit more. i.e. what effects it one way or the other. I've read a bit about it on various sites, but not beinga chemist wasn't sure if the Campden tablets had any effect, or perhaps the acid rest at 133 degrees (I did a double decoction 133/154), or what it was exactly that lower the pH an addition 0.2
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Old 10-25-2009, 06:23 PM   #4
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How sure are you that you've got a really accurate pH meter? I'm not a chemist either, but I took a lot of chemistry, and I remember hearing from a teacher or lab tech that pH meters aren't super super accurate unless you've got a really nice one.
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Old 10-31-2009, 03:31 PM   #5
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I'm working from the numbers provided by the city for the H2O pH and then just using the same method as always for the mash pH. Being that there was a variance in what I have previous got, I was wondering why and what the effects of the lower pH might be in the end.

Like I said, the OG hit it's target and the beer is now fermenting nicely, so I'm not worried about that so much as just wondering if anyone can explain what a lower pH from the mash would normally mean, and possibly explain the variables that effect mash pH.


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