Author Topic: pH woes  (Read 1474 times)

Offline cempt1

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pH woes
« on: February 23, 2016, 12:55:34 PM »
I am new to pH measurement.  I test my 1st 2 batches without filtering out the grains so I have learned that will potentially cause a low reading.  I have a new milwaukee 101 meter.  This weekend I brewed and tested the mash 10 min in and was at 5.5 (bru'nwater estimated 5.4).  I rinsed the meter in RO water and tested distilled water and got 7.5 (I assumed this should be 7).

I am calibrating with the packets that came with the meter which I assume to be diluted giving me erroneous readings.   I will get new solutions but any other newbie pH meter user suggestions?

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Offline Wort-H.O.G.

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Re: pH woes
« Reply #1 on: February 23, 2016, 01:42:06 PM »
I am new to pH measurement.  I test my 1st 2 batches without filtering out the grains so I have learned that will potentially cause a low reading.  I have a new milwaukee 101 meter.  This weekend I brewed and tested the mash 10 min in and was at 5.5 (bru'nwater estimated 5.4).  I rinsed the meter in RO water and tested distilled water and got 7.5 (I assumed this should be 7).

I am calibrating with the packets that came with the meter which I assume to be diluted giving me erroneous readings.   I will get new solutions but any other newbie pH meter user suggestions?

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Ive found freshly opened distilled water tested right away has PH in the 6 range. As it sits out it will dissolve CO2 from the air and the resulting carbonic acid formed can drop the PH lower.

calibration will be the key to most accurate readings. If performed correctly with 2 point calibration (4 and 7 PH solution for brewing purposes) you should be able to get a fairly accurate reading. Your meter resolution capacity and +- accuracy specs define how accurate a reading you can achieve.
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Offline narvin

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Re: pH woes
« Reply #2 on: February 23, 2016, 02:19:34 PM »
Yeah, I wouldn't worry much about testing the pH of distilled water.  Since it lacks buffering, it can vary quickly due to things mentioned like dissolved CO2.

As long as your calibration solution measures correctly, you're ok.  Also, you should be measuring at room temperature.
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Offline brewinhard

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Re: pH woes
« Reply #3 on: February 23, 2016, 09:33:27 PM »
Measuring at room temps include not only the calibration solutions but also your mash sample. I have had best results getting the mash sample temp as close as possible to the temps of the calibration solution as well. BTW, I am pretty sure that those packages of calibration solution that come with the meter in the box are a one time shot. Once you open them, they are not meant for repeated uses.

Offline Wort-H.O.G.

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Re: pH woes
« Reply #4 on: February 23, 2016, 09:35:25 PM »
Measuring at room temps include not only the calibration solutions but also your mash sample. I have had best results getting the mash sample temp as close as possible to the temps of the calibration solution as well. BTW, I am pretty sure that those packages of calibration solution that come with the meter in the box are a one time shot. Once you open them, they are not meant for repeated uses.

good points.

i buy the bottles and just pour out enough to cover the probe.
Ken- Chagrin Falls, OH
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Offline mainebrewer

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Re: pH woes
« Reply #5 on: February 23, 2016, 09:39:48 PM »
I test my 1st 2 batches without filtering out the grains so I have learned that will potentially cause a low reading.

I don't believe that filtering or not filtering out the grain particles will affect the pH reading. I could be wrong, wouldn't be the first or, likely, the last time.
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Offline Wort-H.O.G.

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Re: pH woes
« Reply #6 on: February 23, 2016, 09:42:08 PM »


IME it can .especially chunks sticking to probe.
« Last Edit: February 23, 2016, 09:43:40 PM by Wort-H.O.G. »
Ken- Chagrin Falls, OH
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Offline dilluh98

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Re: pH woes
« Reply #7 on: February 23, 2016, 10:03:48 PM »
Other considerations to proper use of a pH meter:

- Always clean the probe with distilled or RO water between transfers so that calibration solution, storage solution and/or wort solution are not contaminating each other. It's best to have a squirt bottle of distilled water handy for these transitions.

- Always try to take measurements of wort at room temperature. The ion selective glass membrane (the business end of the pH meter) is a delicate thing. If you're working with a non-analytical grade pH meter, it's even more important to take good care as the glass membrane, seals, connections, etc are typically not as robust.

- Get a good storage solution and always keep your probe submerged in it when not in use. pH 4 solution with excess KCl dissolved in it makes a good storage solution.

- pH measurments being logarithmic, it's best practice to recalibrate before each brewing session even if you brew as often as once per week. pH = 5 vs pH = 6 is a tenfold difference in acid concentration.

Offline brewinhard

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Re: pH woes
« Reply #8 on: February 24, 2016, 01:47:19 PM »
I test my 1st 2 batches without filtering out the grains so I have learned that will potentially cause a low reading.

I don't believe that filtering or not filtering out the grain particles will affect the pH reading. I could be wrong, wouldn't be the first or, likely, the last time.

I have found this to not be as effective as using a fully grain/husk free sample.  When I took my very first sample for measuring my pH, I did not strain out the grain/husk material and it read very low (like 5.1).  I thought that was a bit off as I was shooting for a 5.4, so I took another sample and ran it through a fine mesh bag prior to measuring pH.  This one came out around 5.35, so I can only attribute that difference to the grains in the sample taken. I make it a point to only take measurements on samples that have been strained now for more accurate results.

Offline mainebrewer

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Re: pH woes
« Reply #9 on: February 24, 2016, 05:18:52 PM »
I've never filtered my pH sample and my results usually match, within the major of error for my meter, the Brunwater prediction.
I'll take a larger sample next time and filter part of it, now I'm curious to see the difference in the pH of the two samples.
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Offline Wort-H.O.G.

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Re: pH woes
« Reply #10 on: February 24, 2016, 05:44:53 PM »
I've never filtered my pH sample and my results usually match, within the major of error for my meter, the Brunwater prediction.
I'll take a larger sample next time and filter part of it, now I'm curious to see the difference in the pH of the two samples.

when had erratic readings its was usually with darker roasted malts sticking to probe. i could move it around and get 3-4 different readings.

minimal or no malt chunks and moving it around doesn't change or cause erratic readings IME.
Ken- Chagrin Falls, OH
CPT, U.S.Army
https://www.facebook.com/pages/Harveys-Brewhaus/405092862905115

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Cider                         
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Offline brewinhard

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Re: pH woes
« Reply #11 on: February 24, 2016, 06:52:21 PM »
I've never filtered my pH sample and my results usually match, within the major of error for my meter, the Brunwater prediction.
I'll take a larger sample next time and filter part of it, now I'm curious to see the difference in the pH of the two samples.

when had erratic readings its was usually with darker roasted malts sticking to probe. i could move it around and get 3-4 different readings.

minimal or no malt chunks and moving it around doesn't change or cause erratic readings IME.

Agreed.

Offline cempt1

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Re: pH woes
« Reply #12 on: February 25, 2016, 02:33:06 AM »
So, how much do I need to dry off the probe after calibration or testing?   I have been blotting of the outside with a paper towel. I like the idea of the spritzer bottle filled with distilled water.

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Offline hopfenundmalz

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Re: pH woes
« Reply #13 on: February 25, 2016, 03:18:51 AM »
So, how much do I need to dry off the probe after calibration or testing?   I have been blotting of the outside with a paper towel. I like the idea of the spritzer bottle filled with distilled water.

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I never touch the probe. It is put into cleansing solution or storage solution.
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Offline cempt1

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Re: pH woes
« Reply #14 on: February 25, 2016, 11:02:09 AM »
So, how much do I need to dry off the probe after calibration or testing?   I have been blotting of the outside with a paper towel. I like the idea of the spritzer bottle filled with distilled water.

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I never touch the probe. It is put into cleansing solution or storage solution.
I may have miss spoke.  I don't dry off the tip, or the glass part.  I have blotted off the plastic above that.  Seemed to me the rinsing water droplets left on it might affect my reading.  I am probably over complicating it.

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