Author Topic: Ph reading confusion  (Read 407 times)

Offline berry_pride

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Ph reading confusion
« on: September 16, 2018, 04:44:36 PM »
I recently bought the Apera PH60 for testing my ph during the mash and have been noticing some discrepancies in my readings. Here was my most recent process:

1. Calibrate the ph reader
2. 5 min into mash I pull a small sample and put in freezer to cool
3. Once sample reaches 100 degrees I take a reading. This particular time I got 5.3
4. According the beer smith 3 calculator I add 1.6 ml of lactic acid and then stir the mash. I usually get the lactic acid in within 15 mins of starting the mash.
5. After 60 min mash I pull another small sample and cool.
6. After it reaches 100 degrees I test the sample. This time I get 5.33.

What am I doing wrong??? Why is my ph going up??? Any input would be greatly appreciated. Thanks!
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Offline hopfenundmalz

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Re: Ph reading confusion
« Reply #1 on: September 16, 2018, 06:41:25 PM »
I wait longer for the first pull, chill it down to 70+ish, then read it. The Mash will tend to go towards 5.4 usually. Don't worry about a 0.03 difference.
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Offline BrewBama

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Ph reading confusion
« Reply #2 on: September 16, 2018, 06:48:39 PM »
I like to wait about 15-20 min, the pull a sample, cool to room temp (~70*F -ish), as well.

I caution you on using BeerSmith as your acid addition recommendation. I’ve found it was too much acid for me. I’ve found Bru’n water closer to what I need. Of course, YMMV.


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Offline berry_pride

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Re: Ph reading confusion
« Reply #3 on: September 16, 2018, 10:28:45 PM »
I like to wait about 15-20 min, the pull a sample, cool to room temp (~70*F -ish), as well.

I caution you on using BeerSmith as your acid addition recommendation. I’ve found it was too much acid for me. I’ve found Bru’n water closer to what I need. Of course, YMMV.


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Thanks! Now, with that said, is it ok that I don't get the ph adjusted till almost halfway through my mash? Ill check out Bru'n water as well.
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Offline berry_pride

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Re: Ph reading confusion
« Reply #4 on: September 16, 2018, 10:30:07 PM »
I wait longer for the first pull, chill it down to 70+ish, then read it. The Mash will tend to go towards 5.4 usually. Don't worry about a 0.03 difference.

Do you do a 60 min mash typically? Is it that big of a deal that the ph is within target for only half of the total time? Thanks.
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Offline hopfenundmalz

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Re: Ph reading confusion
« Reply #5 on: September 17, 2018, 12:29:41 AM »
I wait longer for the first pull, chill it down to 70+ish, then read it. The Mash will tend to go towards 5.4 usually. Don't worry about a 0.03 difference.

Do you do a 60 min mash typically? Is it that big of a deal that the ph is within target for only half of the total time? Thanks.
I mash for an hour for simple infusion mashes, mix and make sure the target temp is attained during the first 25 minutes, pull and chill pH sample. Measure pH. If  I'm only of  I let it ride. If I'm off a large value I adjust.

It is a good idea to do a mini-mash before had to see if you hit the target. Malt spec sheets should be checked first, which might save that step.
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Online Robert

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Re: Ph reading confusion
« Reply #6 on: September 17, 2018, 01:08:03 AM »
I have often done the scale mash in a saucepan thing when planning a novel grain bill or water profile.  Now I find Bru'n Water an excellent substitute to get me in the ballpark.  In my experience, trying to adjust the pH during mashing is futile.  Almost as soon as grain hits water, the buffer systems are set up and the mash pH will keep pulling toward its natural set point.  You can shift it a bit, but it will move back.  Plan ahead, and then check your actual pH.  If it's off, just take notes, and adjust your water treatment accordingly next time.  You may not be in the ideal range, but don't panic unless it's extreme -- below 5.0 or above 5.8.  And note, pH is to be measured at room temperature, not 100°F.  Alleged "correction factors" are wishful thinking, and higher temperatures will drastically shorten the life of your probe.
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Offline RC

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Re: Ph reading confusion
« Reply #7 on: September 17, 2018, 05:11:47 AM »
In my experience, trying to adjust the pH during mashing is futile.

^This has not been my experience in either a homebrew or commercial setting. Adjusting pH during mashing has always worked for me, whether it's a 10-gal batch or a 35-bbl batch. It takes a bit of experience with different volumes and grain bills to know how much acid to add, but once you dial that in, it's no problem moving a 5.60 mash pH to 5.30, and it's somewhat predictable. But as Robert suggests, if you don't, it'll still be fine. RDWHAHB.

As to your original question, I'd perhaps wait 15 min into a well-stirred mash before taking pH. It should be stable by then. If you add acid, wait another 5-10 min (after stirring well!). Point is you gotta let all the buffering happen before you get a stable pH, and the buffering doesn't happen instantaneously.

Offline berry_pride

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Re: Ph reading confusion
« Reply #8 on: September 17, 2018, 10:55:15 AM »
Excellent! Thank you all for the feedback. I think I am going to to give that scaled mash a shot as well as toying with the bru'n software.
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Offline pfabsits

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Re: Ph reading confusion
« Reply #9 on: October 27, 2018, 05:58:59 PM »
I recently bought the Apera PH60 for testing my ph during the mash and have been noticing some discrepancies in my readings. Here was my most recent process:

1. Calibrate the ph reader
2. 5 min into mash I pull a small sample and put in freezer to cool
3. Once sample reaches 100 degrees I take a reading. This particular time I got 5.3
4. According the beer smith 3 calculator I add 1.6 ml of lactic acid and then stir the mash. I usually get the lactic acid in within 15 mins of starting the mash.
5. After 60 min mash I pull another small sample and cool.
6. After it reaches 100 degrees I test the sample. This time I get 5.33.

What am I doing wrong??? Why is my ph going up??? Any input would be greatly appreciated. Thanks!

A rise in 0.03 pH is insignificant. It is very difficult to obtain +/-0.01 pH. Many factors involved from probe condition (offset and slope), quality of buffers, to even the the temperature of the sample. A pH is to be reported at a specific temperature. A pH of a solution can very by temperature which is separate from the ATC that compensates for the temperature effect on the glass as according to the nernst equation.

On a separate note the influence of adding acid to a solution on the pH measurement is based on the alkalinity. If the water is low in alkalinity the greater the influence. If the water is higher in alkalinity (higher the buffering capacity) the less the influence. RO water has very low alkalinity while groundwater is typically high (especially) in the midwest.

To better understand fill two glasses with RO water. Add a teaspoon of baking soda to one glass. Measure the pH of each. Take an acid like vinegar and count the number of drops it takes to reach pH 4. You will find that the water without baking soda will take 2-3 drops. The one with baking soda will take a very large amount. You can add 100 ml (~1/2 cup) and still not go past pH 6. The reason being is that you increased the alkalinity with the baking soda and until all of the bicarbonate is used up the solution will be buffered against the acid.

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Offline dmtaylor

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Re: Ph reading confusion
« Reply #10 on: October 27, 2018, 08:56:07 PM »
Mash pH is not stable at all.  You'll get different readings from 10 minutes to 20, 30, 40, 50, 60, etc.  It can rise and it can fall.  It doesn't stabilize.  It changes the whole time.  Not by a lot, but not stable.
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