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Old 08-04-2009, 01:03 PM   #1
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Default How much Lactic acid ?

My pH from the tap is 8.05.
How much lactic do I add (per gallon) to get it down to +-6.5 ?
Is the mid sixes the correct pH for sparge water ?
I assume the amount of lactic is dependant on its strength ? How do I get this ?
When I check the pH of the sparge water after adding the lactic how do I adjust the figure to compensate for temperature ?

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Old 08-04-2009, 01:53 PM   #2
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Why not just add a pH buffer into your water such as 5.2? That would ensure that your water is almost perfect for homebrewing without too much work. Check out this link:

Austin Homebrew Supply

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Old 08-04-2009, 01:59 PM   #3
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Im in South Africa, 5.2 is unfortunately not available.

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Old 08-04-2009, 02:10 PM   #4
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JP has an excel spreadsheet that you can use to figure it out. It's available for free download somewhere at howtobrew.com...I don't feel like finding the link right now, though. Just look for brewing water, "understanding your pH", etc.

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Old 08-04-2009, 02:13 PM   #5
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Unfortunately it is impossible to tell from the pH of your tap water alone. You need to know how much of a buffer capacity you water has to be able to predict how much acid you will need to add to get your water to a certain target.

Ideally you would just add enough acid to "max out" the buffering capacity of the sparge water and use neutral water (pH 7) or you could go a little further towards 6.

Compensating for temperature depends on how you are checking the pH. Some digital meters have built in correction. If you are using strips, I would recommend checking with the manufacturer for that correction.

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Old 08-04-2009, 05:13 PM   #6
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Quote:
Originally Posted by Beerrific View Post
Unfortunately it is impossible to tell from the pH of your tap water alone. You need to know how much of a buffer capacity you water has to be able to predict how much acid you will need to add to get your water to a certain target.
+1. Sometimes pH drops down like a stone, sometimes barely moves, when you add the acid.

For my water I add 3-5 ml.
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Old 08-04-2009, 05:38 PM   #7
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Quote:
Originally Posted by rsmith179 View Post
Why not just add a pH buffer into your water such as 5.2? That would ensure that your water is almost perfect for homebrewing without too much work. Check out this link:

Austin Homebrew Supply
Also, just so everyone's on the same page, you actually add the 5.2 stabilizer to the mash, not total brewwater (sparge or top off).
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Old 08-05-2009, 05:57 AM   #8
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Why pH of 5.2 ? Recommended pH for mash and sparge is higher.
You mention 5.2 is added to the mash not the sparge water - I assume the buffer is strong enough to reduce the pH of the sparge water even after the mash has been drained ?
How many ml of 5.2 does it normally take (Im trying to get an idea of how strong it is).

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Old 08-05-2009, 07:49 AM   #9
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pH of hot sample is a bit lower than pH of cold one, ~0.3 pH difference (hot 5.2, cold 5.5). Actually, you should cool the sample down to room temperature for pH measurements, to get consistent values.

About sparge water: I add about 2 ml of 50% food grade lactic acid (or 1 ml phosphoric acid) for each 5L of sparge water. For my moderately hard water, it takes pH down to low 5's or high 4's.

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Old 08-05-2009, 12:10 PM   #10
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Quote:
Originally Posted by Bru View Post
You mention 5.2 is added to the mash not the sparge water - I assume the buffer is strong enough to reduce the pH of the sparge water even after the mash has been drained ?
How many ml of 5.2 does it normally take (Im trying to get an idea of how strong it is).
It isn't as important in batch sparging as it is in fly sparging, but provided your water isn't CRAZY basic, and provided you typically stop sparging at a reasonable point (no lower than 1.012 final runnings), treating sparge water isn't a dire necessity.

pH 5.2 stabilizer is a powder, and it only takes about half a tablespoon per 5gal batch mash. Also, like any buffer, it's only so strong and if you're water is crazy basic it won't work to it's fullest potential. Dilution with DI water is needed then.
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