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Procedure used for measuring mash PH?

Every time I brew I tell myself I will ask the experts on here… When you measure your mash ph (if you do…), do you take it off the top or from the bottom of the tun (output valve). Today I tried from the bottom and measured a 5.05, then a minute or two max after that I stirred and took some from the top and got my typical 5.28.
I am just curious how everyone else does it. Maybe I should have cycled some wort through the bottom before taking the sample. I would like to figure out a good way to do it. I did stir it pretty well before both samples.

Thanks !

Tom

When I did it I would just stir and take it off the top. Surprised you got two different readings

You should wait a good 10-15 minutes after starting the mash, take some clear wort from the top or wherever is convenient, chill the sample to room temp, and take your measurement. After 10 minutes the pH should be pretty stable.

Are you using a pH meter or strips?

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I am using a meter ( apera ph60). I calibrate it just before the brew session.

I do wait for 10-15 min into the brew. And I have always taken off the top after stirring. This time I thought I would open the valve and get a less " chunky" sample , less grain etc. maybe I needed to run more through the bottom to get a better sample.

I will just go back to taking it from the top. I really wasn’t sure what the common practice is for doing it.

Thanks !

It shouldn’t matter so much. Personally I measure right on top. However, it probably is best to stir well before measuring to ensure the most representative sample. Also, be aware that temperature has a very significant effect. If measured warm at mash temperatures around 150 F, the reading will be 0.25 lower than it will be at room temperature. Room temperature is the standard. pH should be about 5.4-5.5 at room temp. If measuring directly in the mash tun (as I do), expect 5.15-5.25.

I have to wonder if you were experiencing a temperature effect.

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I do a water adjustment and check BEFORE dough in… I get close to get 5.8pH… After adding the grist, perhaps 10 minutes, I’ll pull a small sample from the top… I’m constantly whirl pooling my wort… allow to cool and check… By the way… I have like 6 of those baby A&W rootbeer mugs in the freezer… That thick glass cools the wort down quickly… Now, thats lighter colored malt… I do calibrate my meter every time too… So I’m getting comfortable with this procedure and may stop checking pH soon… not today, of course… Sneezles61

I think you may be right with the temp. I let it cool a bit before measuring but it was def warm.

Thanks for all the input guys, I think I have the correct process with all your help. On to the next batch…

Pretty sure that meter has automatic temperature compensation.

Automatic temperature correction is a bit of a misnomer… it corrects for the temperature of the probe itself. It doesn’t correct for the temperature of the liquid you’re testing, which also changes pH with temperature.

Edit - that probably wasn’t clear. Two things change with temperature when you’re measuring pH - the pH of the liquid changes (higher temp = lower pH), and the response of the instrument itself changes with temperature. It’s like a wire - as temperature increases, resistance increases as well in a wire carrying electric current. The temperature correction corrects the response of the sensor based on temperature, but it cannot adjust for the change of pH of the liquid itself based on temperature.

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Why would the probe be a different temperature from the liquid it’s immersed in? Mine gives a temperature reading and the pH. The temperature it gives is typically within one tenth of a degree F of what my Thermapen reads in the liquid.

Sorry - see edit above. Hopefully that makes sense.

I will have to experiment with some readings on the next batch, or maybe I can just play around with some of the cal solution at different temps to learn what the effect is. Thanks for the great info on this topic.

ATC doesn’t do what most people think it does. @porkchop is correct.

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It’s really difficult to homogenize a mash by stirring. So, its not too surprising that the pH differs a bit through the mash. Its easier to homogenize the mash and wort by circulating it through the mash.

With that said, I wouldn’t worry too much that your pH differed. Assuming that the water adjustments were made in pursuit of a proper pH, I wouldn’t worry that a measurement differed from that target. But the measurements are helpful in guiding adjustments for future brews.

I take my first pH measurements at about the 15 minute mark since pH is changing via the variety of reactions and processes that are underway in a mash. I find that pH often continues to change as the mash duration increases. Don’t worry that pH isn’t perfectly on target, but hopefully its close.

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Thanks, I have usually been very close in the past taking my readings off the top. But I end up with a small sample container half full of grain…which it why I thought I would try from the bottom. I prob should have at least recirculated the mash manually using my pitcher before taking the sample.

Thank you Mabrungard… You are the one who’d know… I’ve been tracking my pH and mashing… I see this occurring every time… I enjoy trying to see where this leads… And the piece of the puzzle… the targeted pH varies… So its not an exactly “this precise number”… Sneezles61

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