reality check on BreWater pH calc...

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reality check on BreWater pH calc...

Postby bredmakr » Tue Sep 17, 2002 6:12 am

OK, this just seems unrealistic. So somebody tell me if I'm crazy. I'm trying to calculate how much 85.5% H3PO4 I need to add to drop the pH of 10 gallons of water from 8.0 to 5.7. My water composition includes CA 77mg/L; SO4 52 mg/L; Mg 26 mg/L; Na 15 mg/L; Cl 22 mg/L; Hardness of 306; and Alkalinity of 237.

When I used the BreWater pH adjustment calculator it tells me I need to add 28.1 ml of phosphoric acid. That seems like an aweful lot of acid. Can somebody check my calculations and let me know if my intuition is wrong on this one?
Thanks -
Mike
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Acidify

Postby Freon12 » Wed Sep 18, 2002 1:08 pm

I would not recommend adding that much acid to anything(ok well, Lambic).
Try adding acid to the mash to meet your PH in quantites under the flavor limit.(Don't know exactly, but I don't have to go over 5ml).

I mash in and test the PH after about 5min. if I start out with the high PH water from the tap at about 8.5., it settles at 6.3. With dark beers this is perfect water and ends up at 5.1 by itself, and with lighter beers they tend to drop to 6.3 before any acid.

I calculated .3 drop in PH per ml of lactic acid based on trial and error so 2-3ml max and I end up in the 5.2-5.6 range strongly buffered.(If I try to change it more, it takes alot more acid to make additional change).

I stir it in as to avoid burning any malt.
I hope this idea works for you, Let us know where you end up.

Thanks
Steve.
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I guess I just don't understand mash pH???

Postby bredmakr » Thu Sep 19, 2002 6:13 am

So what I don't understand is do I need to bring the mash and sparge water down to pH 5.6 prior to adding the grain and prior to sparging.

The pH of my water is between 8-8.5. I have been adding gypsum to my water because that is what Papazion recommended to match the style. Now I have a water report that says I have hard water that already matches the English and Irish water profiles pretty well so I though maybe I don't need to be adding gypsum. Then I thought, from what I have been reading about all grain brewing, it appears that I should be acidifying my water for partial mashes, full mashes, to increase mash efficiency. But what you are saying is that I don't need to do that?

To check my own curiosity I finally took a pH reading of one of my finished beers. My House IPA II has a pH of 5.4. This is an extract with specialty grains. So here is the real question, if the beer ends up at what I have been lead to believe is the correct pH range then why do I need to acidify the mash and sparge water? It seems to me that the process takes care of this by itself as a result of the chemical reactions within the mash tun. Am I way off base?

If I do need to lower the pH of my mash and sparge water prior to adding grain and sparging then what should they be? Should I have them both below pH = 6 or do they need to be at different pH values? Should I only worry about the Sparge water pH and not the mash pH? This seems like a possibility b/c if the mash process lowers the pH within the mash tun then I would want to have the sparge water within the same range so as not to shock the enzymatic activity.

Someone please help me with this one. I can often comprehend very complex problems but it is the simple things that get by me and I think this is a very simple thing I just don't understand.
many thanks!
Mike
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Here's the pH Deal

Postby BillyBock » Thu Sep 19, 2002 3:36 pm

Mike:

It took me a long time to get any kind of handle on this subject, so I'll try and distill it for you. I'm going to assume that you're fly sparging.

A mash of 100% pale malt w/ water of pH 7.0 (neutral) will end of with a pH of approx 5.7. Of course you probably already know the addition of specialty malts help acidify the mash as will the addition of certain salts.

What this means in practical terms is this. If you use untreated water (your pH 8.5) to mash this same pale malt, then your mash will probably end up in the pH 6-7 range, not ideal. The target you're shooting for is 5.2-5.5. Of course you know that adding gypsum or calcium chloride will help acidify the mash. But it sounds like you don't want to do this based on your water analysis. So, depending on your grain bill, you'll probably have to add acid to the mash. You can either add it after you've mashed in and checked the pH, or you can treat your mash water before mashing in by acidifying it to pH 7.0. In NE I had water w/ pH of 9.3. If I was making a pale beer, then I acidified the mash water to pH 7.0 first (consider it a helping hand since there were no specialty grains). If I was making a darker beer, then I'd use the water untreated and acifidy the mash after mash-in if needed. I went through alot of trial and error to find something that works for me. Since I use lactic acid I didn't want to add so much that it affected the beer's flavor.

Ok, now the sparge water. You're shooting for a wort pH of 5.0-5.3. Carbonates in the water extract a darker color to the wort. Alkaline water over pH 6.0 extracts tannins from the grain husks leading to astringency. If you want to RDWHAHB, then acidify your sparge water to a pH of 5.7, then just collect the runoff you need. Otherwise, if you sparge w/ your alkaline water you'll need to continually monitor the runoff gravity and pH to avoid extracting tannins. Imagine this....you have a mash at pH 5.2 and are sparging with water at pH 8.5. As you collect wort the alkaline water will eventually replace the wort in the mash tun. The result is your mash pH will be continually diluted and therefore the pH will rise. If you perform the same scenario with sparge water at pH 5.7, it will never get diluted to the point where you'll extract tannins from the husks. Make sense? When I sparge, I like to sit down and have a beer after all that hard work--so I acidify it to 5.7 to not futz with it. After you collect your wort, check the pH and acidify if needed to pH 5.0-5.3. This will help ensure the yeast can get the pH down quickly to help prevent the growth of "bugs". You want you're finished beer to be pH 4.5 and less. The lower the pH, the sharper the character of the beer.

I'm sure if Mesa is out there he can provide a lot more of the chemistry behind this. But, I hope this helps and gives you some perspective. If not, keep asking away. None of us around here mind. See ya.

v/r
Bill
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AH! What it is...

Postby bredmakr » Fri Sep 20, 2002 5:07 am

Thanks Bill,
That was about as detailed of an explanation as I need for right now. Very helpful information and thanks for taking the time to respond. One more question. You say final pH should be 4.5 or less. So, my recent extract IPA with final pH of 5.3 should be an indicator to me that I need to acidify from 8.5 to a more neutral 7.0.
I think I get it now. Still waiting for my Pepo Ale ingredients to arrive. Once they do I'll be mashing away and will be sure to follow up with my results. In the mean time I'll be doing so trial and error testing of my own to figure out the correct doses of acid to lower the pH.

Thanks Again!
Mike
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Wassuup!

Postby BillyBock » Fri Sep 20, 2002 8:01 pm

Mike: On the few occassions I make an extract beer, I either neutralize the water or buy distilled water to ensure the wort pH comes out right. Let me punch the numbers in to Brewater from your original post and I'll report back. I was going to do that and forgot.
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Interesting.....

Postby BillyBock » Fri Sep 20, 2002 9:21 pm

Mike: I just punched in the #s and got the same result. Are you sure you got the hardness and alkalinity #s correct? I seem to remember using 1mL/gal to bring my pH 9.3 water down to 7.0 or 5.7 I can't remember, but I didn't use 28mL.
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water department numbers...

Postby bredmakr » Mon Sep 23, 2002 6:48 am

the hardness and alkalinity are straight from the water quality engineers database for the wellfield serving my neighborhood. I did just notice that both are in terms of Alkalinity as Ca CO3 and Hardness as CaCO3. Then there is a third column with Hardness (Gpg). Not sure what the units are here but I'll find out. I know for a fact that the hardness of the water does run between 250 and 350 in this area. Do not know Ca, Mg contributions. I think that I'll just run some batch tests with the water and go from there.
Thanks Bill.
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