PH goes down after mash???

Hey everyone,

I started my mash today on a Russian Imperial Stout and check the PH, 5.1. At the end of my batch spare I checked it again and now it's 4.7. I thought PH went up as you sparge

This is the second batch where I checked the PH and both times it went down

Thoughts
Toy4Rick

Are you brewing with RO or distilled water?

No. Oceanside city tap water that's is going thru a charcoal filter

Toy4Rick

A couple of thoughts:

1) Are you cooling a sample to room temp before taking a reading? Even if your meter has ATC, it's best to take measure a cool sample. Know that the pH target will be different so take that into account.

2) Most people don't like to hear it, but I would never trust a meter under $200 for less than 10 minutes without recalibrating. (Not that you can't get great results from a cheaper meter, assuming you know it's limitations and use it correctly) There will certainly be those with good results, but it's my rule of thumb. Pour or mix fresh 4 and 7 buffers, and calibrate again. If you want to test your meter's stability, there is a sticky in the Brew Science section dealing with that.

I'm checking my PH with a test strip, dip and read method

Toy4Rick

Temperature has an effect on pH. Make sure to cool to room temp before checking.

Maybe I am missing something here

Start the mash, temp is ~154*, PH is 5.1
1 hour later after sparging the temp might be ~165, PH is 4.7

How long does it take the little pad on the end of the strip to cool before reading?

Toy4Rick

What temp did you sparge at? What was the grain bill?

It's possible sparging released tannins or other acidic compounds.

Toy4Rick said:

Maybe I am missing something here

Start the mash, temp is ~154*, PH is 5.1
1 hour later after sparging the temp might be ~165, PH is 4.7

How long does it take the little pad on the end of the strip to cool before reading?

Toy4Rick

Click to expand...

Actually, you need the wort to cool before dipping the strip into it. They are not meant to work at high temperatures. You then have to compensate for the temperature diffference.

According to Gordon Strong (Brewing Better Beer) the strips are meant to work with wort that is room temperature (about 68degF). You then subtract 0.3 from the reading to get the results for Mash temperature.