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Old 03-31-2012, 04:47 PM   #1
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Default Mash pH too low?

I picked up a Milwaukee pH meter, with the Auto Temp Correction probe. MW200 I think is the part number. Received it two weeks ago, calibrated it and used it once already.

I'm brewing up a Brown Ale now, and towards the end of the mash took my pH reading. Was distracted by dog sitting and didn't take it earlier.

At 150*, the reading was 5.15.
I cooled the temp down to 120* and checked again, and reading was still 5.15.

While realizing I should cool the wort some more to help preserve the electrode, do I still need to cool it to room temperature, even with the ATC? I am seeing that advice out there.

Also - is my pH too low?

Using the water primer, and using 5.3% of grain as roasted chocolate malt, I did not add any acidulated malt. I did add extra Calcium Chloride and Gypsum for a more English, minerally profile.

Used 20g of Calcium Chloride, and 8g of Gypsum to treat 12 Gallons of water. Of which 6 gallons was used for the mash. I end up treaing my mash water, plus additional mash out and sparge water, all together. Less the few extra gallons of water I add to have enough to finish the sparge.

Using Boston tap water, which pretty much starts close to RO.
Calcium = 4 ppm
Magnesium = 1 ppm
Bicarbonate = 10 ppm
sodium = 1- ppm
Chloride = 14 ppm
Sulfate = 8 ppm
Water pH = 7.9
RA as CaCO3 = 5

Trying to get deeper into the water chemistry aspect of this. How'd I do?

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Old 03-31-2012, 05:19 PM   #2
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The Roast malts will add to the Acidity, or lower your pH. But you are still in the ideal target range for your mash pH (5.1-5.5) According to JP

If your pH gets too low, mash enzymes don't work as well and can even denature or cook. (think of civiche, fish cured in citrus juice at room temp). If your pH gets too high or basic you can start extracting tanins (think ice tea aftertaste) or other harsh flavors from the grain husks. I think this starts to occur around pH 7 and above, but don't quote me on that.

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Old 03-31-2012, 06:48 PM   #3
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Quote:
Originally Posted by luke2080 View Post
I picked up a Milwaukee pH meter, with the Auto Temp Correction probe. MW200 I think is the part number. Received it two weeks ago, calibrated it and used it once already.
If that means you calibrated it 2 weeks ago then the readings are meaningless. It must be calibrated every time you use it (by which I mean once per brew day at least).


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Originally Posted by luke2080 View Post
At 150*, the reading was 5.15.
I cooled the temp down to 120* and checked again, and reading was still 5.15.
You should not measure pH at such a high temperature. Many of the inexpensive probes will not handle temperature that high and may be damaged. Even the ones that can will have their useful lives shortened by such high temperature (or, really, the thermal stresses to which the bulb is subject when going from room to hi temp. and back to room).

All measurements (calibrating buffers and samples) should be made at the same (room) temperature. All recently published values (there may be confusion in older texts) are room temperature values.

Quote:
Originally Posted by luke2080 View Post
While realizing I should cool the wort some more to help preserve the electrode, do I still need to cool it to room temperature, even with the ATC? I am seeing that advice out there.
Unless you have verified that the isoelectric pH of the electrode is 7 (see Step 11b in the stickies) you should not make any demands on ATC. All measurements should be made at the same temperature.


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Originally Posted by luke2080 View Post
Also - is my pH too low?
Using the water primer, and using 5.3% of grain as roasted chocolate malt, I did not add any acidulated malt. I did add extra Calcium Chloride and Gypsum for a more English, minerally profile.
Your mash pH should be around 5.6 at room temperature if using only 5% black malt. It is hard to say exactly where it will fall without analyzing the grist but I would be surprised if the real mash pH were as low as 5.15. But then I've been surprised before.


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Originally Posted by luke2080 View Post
Used 20g of Calcium Chloride, and 8g of Gypsum to treat 12 Gallons of water.
That's a lot of salts! If you like your beers that salty then that's OK but it's a lot to start with IMO.
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Old 03-31-2012, 07:58 PM   #4
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Those JP mash pHs are at mash temp measurement. Its odd that the OP continued to see a similar pH when the sample cooled. It suggests that the meter might have fallen out of kilter with the high temp excursion.

The recorded pH is at the low end so be more aware of avoiding any acidity increasing additions in the future. An option in the case of the OPs water is to avoid adding any Ca or Mg additions in the mash water and adding those minerals directly to the kettle to avoid depressing the water's RA any more. The extra minerals that were added in the OPs example worked against him and helped depress the pH too low.

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Old 03-31-2012, 08:18 PM   #5
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Quote:
Originally Posted by ajdelange View Post
If that means you calibrated it 2 weeks ago then the readings are meaningless. It must be calibrated every time you use it (by which I mean once per brew day at least).
Well that was my next question...how often does it need calibration. I'll be sure to do that before every use going forward.

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Originally Posted by ajdelange View Post

All measurements (calibrating buffers and samples) should be made at the same (room) temperature. All recently published values (there may be confusion in older texts) are room temperature values.

Unless you have verified that the isoelectric pH of the electrode is 7 (see Step 11b in the stickies) you should not make any demands on ATC. All measurements should be made at the same temperature.
I'll read that sticky, but what is the point of the ATC then? I understand cooling the wort to lengthen the tools life. But I also want a quick reading (if doing this earlier in the mash) to see if adjustments are needed. Is buying a pH meter with ATC just a waste of money?

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Originally Posted by ajdelange View Post

That's a lot of salts! If you like your beers that salty then that's OK but it's a lot to start with IMO.
From the water primer sticky.... using 5g of Calcium Chloride = 1 tsp, and ~4g Gypsum = 1 tsp. Had 12 gallons of water to treat. So with that, from the baseline I would need 12 grams of Calcium Chloride wouldn't I?

Trying to follow a more British style for this I followed the instruction of
Quote:
For British beers: Add 1 tsp gypsum as well as 1 tsp calcium chloride
But these instructions were for 5 gallons, so I doubled that. So I was shooting for a little minerally....but if my math is off please avoid laughing too much and let me know. Had enough people laugh at my terrible ability on the golf course already yesterday.

Thanks for the input.
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Old 03-31-2012, 08:23 PM   #6
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Quote:
Originally Posted by mabrungard View Post
Those JP mash pHs are at mash temp measurement. Its odd that the OP continued to see a similar pH when the sample cooled. It suggests that the meter might have fallen out of kilter with the high temp excursion.
Yep - will have to calibrate my meter everytime...and I guess just be sure to take the reading at 70*F.

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Originally Posted by mabrungard View Post
The recorded pH is at the low end so be more aware of avoiding any acidity increasing additions in the future. An option in the case of the OPs water is to avoid adding any Ca or Mg additions in the mash water and adding those minerals directly to the kettle to avoid depressing the water's RA any more. The extra minerals that were added in the OPs example worked against him and helped depress the pH too low.
So I could have added some of those salts right into the kettle? I should have checked a water calculator to see what it expected would happen. I just downloaded your Bru'nWater sheet.

Appreciating all of the feedback. I view water chemistry as the final frontier for my brewing.
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Old 03-31-2012, 09:11 PM   #7
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I agree with AJ that an instrument like a pH meter should be calibrated for every brew day. That helps reduce the potential of drift in the meter or probe. ATC is a nice feature, but its utility in mashing is dubious. I've included a short write up on ATC in the Water Knowledge page of the Bru'n Water website. Be sure to read that over to add a little more info for your brew day. I think the article that AJ posted on the Brewing Science forum on pH Meters also discusses the lack of utility of ATC in brewing.

I guess in the case of those mineral additions, it might have been a good double check to have used one of the mineral addition calculators to see what the resulting ion concentrations were. Bru'n Water has that feature along with guidance to help brewers avoid overdosing their wort. Live and learn. That beer should still be drinkable and will give you a reference point as to what that level of mineralization tastes like. Do revisit the mineral additions and calculate what those resulting ion concentrations are so that you can help calibrate your palate.

With so many facets to brewing, water can be one of the last frontiers for most brewers. When you think your beer still needs help and you think you're doing everything else correctly, then its time to add brewing water chemistry to your training. You are fortunate that the tap water has so little mineralization. It should be good for a good variety of paler colored beers. When you start to delve into darker beers and those with high crystal content, then you may need to learn to add alkalinity to improve those beers.

Enjoy!

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Old 03-31-2012, 09:13 PM   #8
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Quote:
Originally Posted by luke2080 View Post
I'll read that sticky, but what is the point of the ATC then? I understand cooling the wort to lengthen the tools life. But I also want a quick reading (if doing this earlier in the mash) to see if adjustments are needed. Is buying a pH meter with ATC just a waste of money?
Some say yes but I'm not one of them. If ATC is not available then buffer and and sample temperatures must be exactly the same and you have to measure/adjust them yourself (use a water bath for example). If ATC is present it does have the potential to mislead you but the closer the three temperatures are the less that potential. If they are exactly the same it doesn't matter if the isoelectric pH is 1 or 13 - no error will be introduced. If the isoelectric pH is between 6.5 and 7.5 (which it is for most electrodes but I do have one at 8.3) the amount of error introduced by say 5 °C temperature difference is about the same as the buffer manufacturing uncertainty. The really nice thing about ATC is that you don't have to measure anything. Just look at the meter's display during cal and sample measurements to be sure they are within a few degrees of one another.



Quote:
Originally Posted by luke2080 View Post
From the water primer sticky.... using 5g of Calcium Chloride = 1 tsp, and ~4g Gypsum = 1 tsp. Had 12 gallons of water to treat. So with that, from the baseline I would need 12 grams of Calcium Chloride wouldn't I?
You are, alas, another victim of less than clear wording. The Primer is intended to say that the baseline is 1 tsp CaCl2 /5 gal and that if doing a British beer one would use 1 tsp CaCl2 and 1 tsp gypsum /5 gal. Thus for 10 gal you would need 2 tsp of each. Unfortunately you can interpret it to mean that the 1 plus 1 is in addition to the 1 tsp for the baseline which would lead you to conclude that for 10 gal you would need 4 tsp of CaCl2 and 2 of gypsum.
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Old 04-01-2012, 04:59 PM   #9
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Thanks for the feedback. Looks like I've got my topic to read up on some more on this lazy sunday.

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