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Old 08-22-2013, 10:00 PM   #1
brewmeister13
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Default Problems hitting PH

I've brewed two all grain batches now and both times my mash pH has been quite a bit above the estimate of Bru'n Water. My process is that I transfer the hot water to the MT and dough-in. After about 5 minutes I pull a sample and cool it quickly in an ice bath down to 77F or so. The meter is new and calibrated before both brew days.

My first batch was estimated at 5.4 and came in at 5.8. I started with distilled water and this is what was added:

9 lbs Maris Otter
10 Oz Vienna
10 Oz Munich
4 oz Crystal 60
1 oz Acid malt

6 Gallons water
3.6 g Gypsum
1.2g Epsom Salt
1.3g Baking Soda
3.6g Calcium Chloride

Mashed at 1.25 qts/lbs or about 15 quarts

After posting up here I learned that I should have left out the baking soda and that some of the problems may have come from the salts precipitating out of the water in the HLT (there was some chalk looking material at the bottom when I went to clean up.

For my second batch the estimate was 5.3 and again I came in at 5.8 prior to adjusting with Lactic Acid. This batch again was distilled water and I added the following:

8.25 lbs Maris Otter
1lb 11oz toasted Oats
1 lb Chocolate malt
12 oz Crystal 120
8 oz English Roasted Barley
8 oz Victory
8 oz Coffee malt
8 oz rice hulls

1.2g pickling lime
.6g Calcium Chloride
.4g Gypsum
.8g Epsom Salt
.8g NaCl

Again I mashed at 1.25 qts/gal or about 17 quarts. This time I added the salts directly to the MT with the grain.

Why are my measured pH's coming up so much higher than the estimated ones? And should I assume that my estimate is .5 pH higher than what I will see on brew day?

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Old 08-23-2013, 02:14 AM   #2
mabrungard
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Hmm? It sure seems that the mash pH should have been quite low with those acidic grists. That is quite a discrepancy in the prediction, but it happens sometimes.

All of the salts you were adding are highly soluble, so it appears that you didn't stir the HLT enough and those salts went straight to the bottom. That may have increased the RA of the mash water.

In addition, you are adding highly soluble bases to the mash water and collecting a sample very early after the dough in. It is very possible that the reactions have not had a chance to occur yet.

A more important question is regarding the mixing of your grist and volume of water under a false bottom and if there is any wort circulation prior to collecting the pH sample? Incomplete mixing of the grist and wort could easily produce areas that have higher or lower than desired pH.

Although its possible that the program totally screwed up the estimate, I expect that there were a few procedural complications in the mashing and sampling that skewed the results. An error of 0.5 is off by a mile and I've never heard of or seen a case that was that far off when using Bru'n Water properly. Revisit your mashing, mixing, and recirculation procedures and it appears that delaying the sample collection a few more minutes would be wise.

Good luck.

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Old 08-23-2013, 02:25 AM   #3
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Try using Brewer's Friend advanced water calculator. Here.
You can add your grist and adjust your pH with whichever acid you desire.

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Old 08-23-2013, 02:41 AM   #4
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While it is true that no mash pH prediction is going to be spot on a mash pH as high as 5.8 with grists which contain dark malt and sauermalz is suspicious although enough baking soda or lime could completely neutralize the acids. That's what they are therefore - to neutralize excess acid from the dark malts. If you are using alkali for that purpose don't use sauermalz.

A major part of the art of using a pH meter is spotting funny looking readings. 5.8 is a funny looking reading under the conditions you describe. When you see a reading like that the first thing you should do is rinse (with DI water) and shake/blot dry your electrode and then stick it in pH 4 buffer. It should read very close to pH 4. If it does not that means your calibration is invalid. It is characteristic of inexpensive meters that they are unstable. A new meter should be checked for its stability characteristics and it should be calibrated as often as the stability checks indicate is necessary. See the Sticky on pH meter cal for more details.

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Old 08-23-2013, 04:23 PM   #5
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Quote:
Originally Posted by mabrungard View Post
A more important question is regarding the mixing of your grist and volume of water under a false bottom and if there is any wort circulation prior to collecting the pH sample? Incomplete mixing of the grist and wort could easily produce areas that have higher or lower than desired pH.
I think my mixing was good. I actually mixed it so much that I missed my mash temp by 10F, but that is something that I will work on in the future. I am unsure of the volume of water under the false bottom and don't do any circulation to avoid losing heat in the process. Could that really account for .5 higher pH than expected?

Quote:
Originally Posted by ajdelange View Post
While it is true that no mash pH prediction is going to be spot on a mash pH as high as 5.8 with grists which contain dark malt and sauermalz is suspicious although enough baking soda or lime could completely neutralize the acids. That's what they are therefore - to neutralize excess acid from the dark malts. If you are using alkali for that purpose don't use sauermalz.

A major part of the art of using a pH meter is spotting funny looking readings. 5.8 is a funny looking reading under the conditions you describe. When you see a reading like that the first thing you should do is rinse (with DI water) and shake/blot dry your electrode and then stick it in pH 4 buffer. It should read very close to pH 4. If it does not that means your calibration is invalid. It is characteristic of inexpensive meters that they are unstable. A new meter should be checked for its stability characteristics and it should be calibrated as often as the stability checks indicate is necessary. See the Sticky on pH meter cal for more details.
The alkali and acid malt used in the first recipe was something that you helped me see the counter productivity of in some of my earlier posts; thank you. Which is what concerned me about the stout mash. Without the lime my estimated pH was 5.0.

I think my meter is decent in its calibration and stability. I have a Milwaukee 101 meter with manual temp correct, but I was always within a few degrees of 77, which is what I calibrated it with. After a full brew day and 2 months of storage the meter was only off by a few hundredths with pH4 solution and less than a tenth off of pH7, but I will definitely try the pH4 solution in between next time to make sure. I will also try checking every 5 minutes, like the sticky talks about, until the reading is stable. However, I was under the impression that corrections to pH needed to be made fairly quickly due to the quickness of starch conversion. After my initial high reading I added a few drops of lactic acid (my acid malt had been invaded by bugs) and retested and it came in at 5.35. Could this have been more because of the elapsed time and not the acid addition?

I apologize for my ignorance on the subject and greatly appreciate your guys' help.
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Old 08-23-2013, 08:41 PM   #6
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Quote:
Originally Posted by brewmeister13 View Post
The alkali and acid malt used in the first recipe was something that you helped me see the counter productivity of in some of my earlier posts; thank you. Which is what concerned me about the stout mash. Without the lime my estimated pH was 5.0.
Without having measured the particular lots of the particular grains you are using one cannot really predict mash pH that well. My inclination based on experience would be that you would get something like 5.5. Adding alkali to that might get you to 5.8. But I'm only telling you what my intuition says - not asserting that a sans-alkali pH of 5.5 is highly probable. It would explain things but that doesn't make it the right answer. Where it's possible I recommend a test mash i.e. mash a small portion of the grains (be sure to get a uniform sample) prior to committing the whole mass of grain.

Quote:
Originally Posted by brewmeister13 View Post
I think my meter is decent in its calibration and stability. I have a Milwaukee 101 meter with manual temp correct, but I was always within a few degrees of 77, which is what I calibrated it with. After a full brew day and 2 months of storage the meter was only off by a few hundredths with pH4 solution
That's pretty good

Quote:
Originally Posted by brewmeister13 View Post
and less than a tenth off of pH7,
and that's pretty good too but definitely enough that recal is necessary. An instrument that reads to 0.01 should be good to withing 0.02 or so over a period of a half hour and a good meter will stay that stable for hours.

Quote:
Originally Posted by brewmeister13 View Post
but I will definitely try the pH4 solution in between next time to make sure. I will also try checking every 5 minutes, like the sticky talks about, until the reading is stable.
That's a good plan but you should also do the reading every 5 minutes in buffers to see how long your meter will hold its calibration. Readings may drift or they may wanter (+ and - deviations) or they may hold stable.

Quote:
Originally Posted by brewmeister13 View Post
However, I was under the impression that corrections to pH needed to be made fairly quickly due to the quickness of starch conversion.
The quicker you can get the correction done the better. With rapidly changing pH in the first few minutes, as is sometimes seen, there isn't much you can do except wait things out. This is one reason I so strongly recommend test mashes. With properly executed test mashes you should hit the desired pH pretty quickly and without and further adjustments.

Quote:
Originally Posted by brewmeister13 View Post
After my initial high reading I added a few drops of lactic acid (my acid malt had been invaded by bugs) and retested and it came in at 5.35. Could this have been more because of the elapsed time and not the acid addition?
No, I don't think so. With lactic acid things should stabilize pretty quickly after and acid addition. With sauermalz it has been my experience that the pH plummets early on to eventually rise and then level off as the acid dissolved off the sauermalz is realeased and reacts with the base malt(s).

Quote:
Originally Posted by brewmeister13 View Post
I apologize for my ignorance on the subject and greatly appreciate your guys' help.
No need to do that. Few are born with complete brewing knowledge pre loaded.
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