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Old 10-15-2013, 05:28 PM   #1
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Default Bru'n water pH puzzle

Second AG brew last weekend, so forgive me if this is a newbie question...

Bru'n water overestimated the amount of Lactic Acid I needed to bring my mash pH down to 5.2.

I took careful notes during the mash, and now I've gone back in and double checked everything, and I come up with the same results, so all really obvious gaffs eliminated. All measurements taken by removing a small mash sample, cooling to room temp, and using a calibrated (that morning) Hanna pHep 5 meter.

I fine tuned the vols and grains in the spreadsheet and I've input all my water salts (minimal). The spreadsheet is still telling me to add 4.8mL of lactic acid, but when I did that during the mash, I got a pH of 4.98.

I expected it to be within a few hundredths of 5.2. Any ideas? (pdf of worksheets att'd since xls not allowed). The only thing I could come up with is that I had pretreated the water with 1 campden tab per 6 gallons and maybe that had an effect (?)

For extra credit, I adjusted pH back to 5.23 by adding 1g of slaked lime (lucky guess on the amount), would you have done the same or different?

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Old 10-15-2013, 05:45 PM   #2
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I would guess since you have a fair amount of roasted grains the degree of roast could make a difference? I know that LHBS sometimes cautions me if they are on top of it to ease back on a particular roast if it is either too light or too dark than normal. Martin could be of more help, he wrote it I believe.

Also, if your water is fairly soft, pH can flucuate much easier than with a water with more carbonate (alkalinity)

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Old 10-15-2013, 06:03 PM   #3
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To estimate mash pH is a fairly simple matter. You compute the proton deficit of your water at the desired mash pH. You do the same for the base malt and any specialty malts that have a proton deficit at the desired pH. You compute the proton surfeit of any specialty malts that have a proton surfeit at the target pH. You add up all the deficits and subtract all the surfeits and, unless your beer has lots of dark malt, there will be a deficit which is made up by adding lactic acid. As the properties of lactic acid are well known it is easy to determine how much to add to balance a particular deficit. It is also easy to determine the deficit of water of known alkalinity. This is where 'easy' ends. It is not easy to determine the proton deficits or surfeits of malt without making an elaborate set of measurements on each and this means each of the malts you are actually using. If you don't do that then you can only estimate what the deficits or surfeits might be at a particular pH based on the malts' colors or measurements done by someone else. There are some of these abroad but they were not done rigorously so the data is approximate. As such you can only get an approximate estimate of the amount of acid needed. The smart camper uses the spread sheeet or calculator as a guide and adds the acid in increments checking pH as he goes. Better yet, he makes a test mash, determines how much acid it takes to get that to proper pH and then scales the answer to the size of the full mash.

Slaked lime is fine for mash pH adjustment but it may take more than you calculate because some of the calcium reacts with malt phosphate thus releasing acid which neutralizes some of the lime's alkalinity. This doesn't matter as the calcium is precipitated and the neutralized alkalinity is only water.

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Old 10-15-2013, 06:43 PM   #4
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I live fairly near the OP. My water's chemistry is quite variable. Do you get your water from SNEW? Did you have it tested yourself? You can probably get a more complete report from your municipality, which would be good to compare to your test results. I had two tests on my water and they're not even close. I think the only way to be sure of what's in your water on any given day is to start from RO or DI water and add minerals from there.

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Old 10-15-2013, 09:57 PM   #5
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I like to shoot for 5.4 in the middle rather than 5.2 or 5.6 on the edges of the zone.

I generally put Rye Malt in as a base malt, which change the acidity in the mash calculation. If that was a roasted malt, then add it such. It may also be why you chose to use Chalk to add alkalinity to raise the predicted mash pH.

It seems like the whole 4 ml addition of lactic acid was not necessary, and would likely have gotten you close to 5.3 without the lime addition. I am jealous of your brewing water... I have to use R/O.

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Old 10-16-2013, 05:41 PM   #6
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Quote:
Originally Posted by ajdelange View Post
To estimate mash pH is a fairly simple matter. You compute the proton deficit of your water at the desired mash pH. You do the same for the base malt and any specialty malts that have a proton deficit at the desired pH. You compute the proton surfeit of any specialty malts that have a proton surfeit at the target pH. You add up all the deficits and subtract all the surfeits and, unless your beer has lots of dark malt, there will be a deficit which is made up by adding lactic acid. As the properties of lactic acid are well known it is easy to determine how much to add to balance a particular deficit. It is also easy to determine the deficit of water of known alkalinity. This is where 'easy' ends. It is not easy to determine the proton deficits or surfeits of malt without making an elaborate set of measurements on each and this means each of the malts you are actually using. If you don't do that then you can only estimate what the deficits or surfeits might be at a particular pH based on the malts' colors or measurements done by someone else. There are some of these abroad but they were not done rigorously so the data is approximate. As such you can only get an approximate estimate of the amount of acid needed. The smart camper uses the spread sheeet or calculator as a guide and adds the acid in increments checking pH as he goes. Better yet, he makes a test mash, determines how much acid it takes to get that to proper pH and then scales the answer to the size of the full mash.

Slaked lime is fine for mash pH adjustment but it may take more than you calculate because some of the calcium reacts with malt phosphate thus releasing acid which neutralizes some of the lime's alkalinity. This doesn't matter as the calcium is precipitated and the neutralized alkalinity is only water.
Okay, AJ, so then bottom line, what you're saying is that I shouldn't expect Bru'n Water to be very accurate, I should use it as an initial indication and incrementally add lactic acid to zero in on my desired pH. Do I have that right?

If so, I can live with that.
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Old 10-16-2013, 05:48 PM   #7
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Quote:
Originally Posted by mchrispen View Post
I like to shoot for 5.4 in the middle rather than 5.2 or 5.6 on the edges of the zone.

I generally put Rye Malt in as a base malt, which change the acidity in the mash calculation. If that was a roasted malt, then add it such. It may also be why you chose to use Chalk to add alkalinity to raise the predicted mash pH.

It seems like the whole 4 ml addition of lactic acid was not necessary, and would likely have gotten you close to 5.3 without the lime addition. I am jealous of your brewing water... I have to use R/O.
Matt:

Yeah, for the most part, I like my water too. The only caveat is that because it's city water, the source can vary with the seasons. So far, I've based all my water chemistry on a single Wards report done last summer. I may pull another one soon just to have a baseline.

My water salting routine is pretty minimal, but I do believe that in most cases I will need a little acid addition to get pH down to the middle of the zone. I guess shooting for the middle is a good idea until I get a particular recipe dialed-in.

Whether a malt is a base, crystal, or roasted is still a bit of a mystery to me. I've been inputting anything that says "Caramel" or "Crystal" in the product write-up as Crystal. Is that right? I wouldn't have thought to put "Base Malt" for anything but 2-Row.
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Old 10-16-2013, 05:57 PM   #8
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Quote:
Originally Posted by satph View Post
I live fairly near the OP. My water's chemistry is quite variable. Do you get your water from SNEW? Did you have it tested yourself? You can probably get a more complete report from your municipality, which would be good to compare to your test results. I had two tests on my water and they're not even close. I think the only way to be sure of what's in your water on any given day is to start from RO or DI water and add minerals from there.
Hay Satph - Yes, we are in the 2nd district and get our water from SNEW, and yes, I sent a sample to Ward to test it for me over the summer (water report att'd - hope this helps). Caveat - I use an Everpure 300 water filter to improve the taste of my drinking water, and I use that water for brewing. I believe this is mostly the difference between the muni water report and Ward's.

As for what I said above about a city water source quality varying during the year, and given ours is largely from reservoirs, have you seen this timely little item on the home page of the SNEW web site? Just noticed it now:
"Water Quality Issue – Issued October 15, 2013

We have observed a yellowish tint in the water for the past several days. This is due to a higher than usual level of manganese in the treated water. Several adjustments have been made but the issue has persisted. Manganese is a secondary standard that is an aesthetics issue - versus primary standards which are health related.

The reservoir experiences a turnover every year as the temperature cools and the bottom water surfaces to the top and changes the incoming water quality. This increases the incoming manganese levels and this turnover is currently happening. We have made operational adjustments to try to correct the issue and are still working towards correcting the problem. We will continue monitoring our system and making operational adjustments as necessary until the water quality returns to normal.

To the extent possible, try to refrain from washing fine, expensive whites until the water returns to normal."
Seriously?? Clearly these people are not brewers or they wouldn't be chattering about something so meaningless as fine whites!!!
File Type: pdf 28Wilson-Water1.pdf (71.5 KB, 15 views)
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Old 10-16-2013, 06:01 PM   #9
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Quote:
Originally Posted by satph View Post
I live fairly near the OP. My water's chemistry is quite variable. Do you get your water from SNEW? Did you have it tested yourself? You can probably get a more complete report from your municipality, which would be good to compare to your test results. I had two tests on my water and they're not even close. I think the only way to be sure of what's in your water on any given day is to start from RO or DI water and add minerals from there.
Hey, Satph:

Can you PM me or post a copy of the water reports you had done?

Thx!
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Old 10-16-2013, 06:12 PM   #10
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It sounds like everyone has a bit of the puzzle figured out here. If you have a stable water source, you may be fine with simply brewing a few times, tweaking the expected pH to get a good prediction, and then use that as a standard from then on.

If your water changes over time, and a lot of places do, then you probably really want to test the water or pH each time you brew in order to get an accurate calculation.

Frankly, I haven't had my water checked in a few years. I have begun to wonder if it's time to do it again, and maybe more often from now on. I know our water doesn't change a LOT over time, but could change some over a lot of time.

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