Mash pH 4.6??

I finally bought a pH meter and tested my mash pH. I was surprised to find that it read 4.6. I've read that 5.2 to 5.4 is the ideal range. I've also read that pH climbing too high, 5.8 and above is generally the problem. I bought some lactic acid to adjust it with in case it was too high.

What I didn't expect is that my pH would be too low. It was 4.6 in my mash and 4.6 during my sparge.

Is this possible? I use RO water and add Gypsum, Calcium Chloride, etc appropriate for the style I'm brewing if that makes a difference...but this is the first time I've tested the pH. I've also ordered some new calibration solution to rule that out.

If anyone has any ideas or comments on this I would appreciate it!

Thanks!

stewart194 said:

I finally bought a pH meter and tested my mash pH. I was surprised to find that it read 4.6. I've read that 5.2 to 5.4 is the ideal range. I've also read that pH climbing too high, 5.8 and above is generally the problem. I bought some lactic acid to adjust it with in case it was too high.

What I didn't expect is that my pH would be too low. It was 4.6 in my mash and 4.6 during my sparge.

Is this possible? I use RO water and add Gypsum, Calcium Chloride, etc appropriate for the style I'm brewing if that makes a difference...but this is the first time I've tested the pH. I've also ordered some new calibration solution to rule that out.

If anyone has any ideas or comments on this I would appreciate it!

Thanks!

Click to expand...

I don't think it's possible, with RO water and a little CaS04 and CaCl2. Especially if the sparge reading was the same.

Did you calibrate your pH meter right before use? And is it accurate in the buffers?

Thanks Yooper. It was calibrated properly the morning that I brewed, but it's a super cheap pH meter I found on Amazon. I thought I'd try new pH solution first before replacing the meter.

But isn't the pH of the sparge typically higher than the mash pH?? It was the same, 4.6 all the way through the brewing process. I tested it throughout and made sure it was around 68 degrees each time I took a reading. (That is the temp that the instructions for my pH meter said were supposed to be the most accurate)

stewart194 said:

Thanks Yooper. It was calibrated properly the morning that I brewed, but it's a super cheap pH meter I found on Amazon. I thought I'd try new pH solution first before replacing the meter.

But isn't the pH of the sparge typically higher than the mash pH?? It was the same, 4.6 all the way through the brewing process. I tested it throughout and made sure it was around 68 degrees each time I took a reading. (That is the temp that the instructions for my pH meter said were supposed to be the most accurate)

Click to expand...

Not only is the sparge pH higher than the mash normally, the mash pH changes as well with each reading. The first reading, 15 minutes in, will be different than the second reading (if you take one) and very different from the one of the wort going into the kettle. If that was the same, and so low, that is troublesome.

Interesting. I took my first Mash reading 15 minutes in, since that is what I read...that it takes about that amount of time for the pH to settle out. Then I took another reading at 30, another at 45, and another well over an hour after it was already in my brew kettle. I checked my Sparge the same way, at the beginning and again after 10 minutes. Then I took a final reading of the mash and sparge combined in the brew kettle. One time it read 4.7, but every other time it read 4.6. I can't remember which time read 4.7.

Sounds like I might have a screwy pH meter.

It would be difficult for the RO or distilled water mash to reach a pH less than 5 unless there was a large amount of roast and/or crystal malts and a large dose of gypsum or calcium chloride. Of course, if the grist also included acid malt, then you could drive it down effectively with that too. But for the most part, I don't think its likely that a normal mash would fall that low. The Reaper's Mild recipe is one of the most acidic grists I've ever seen and it would only fall to 4.9 to 5.0 when using RO water w/ minor minerals.

Do revisit the meter calibration.

Thanks to both of you! I will check my pH meter with new calibration solution.

Also, are you taking a sample of the mash and cooling it before taking the pH? Your pH reading will decrease with increasing temperature. At mash temps, it's about 0.35 pH points below the same reading taken at "room temperature."
4.6 is pretty low, so I doubt that's the whole story. Recalibrating is a great suggestion, but also check what your manual says about taking pH readings at elevated temperatures. Some meters have "automatic temperature control" (or a similarly named feature), but that doesn't compensate for the actual change in pH with temperature, it only ensures that the meter reads correctly at different temperatures. (And, at mash temperatures, the pH of the mash is -0.35 below what it would be at "room temperature.")
If you have any of that 5.2 buffer, mixing a small amount of that up would be a great way to test the meter in a brewing relevant range. (Testing at pH 4 and pH 7 should be good enough, though.)

Chris Colby
Editor
beerandwinejournal.com

Thanks for the reply Chris. I did take the hot wort and put it in the freezer for each reading. After 20 minutes or so in the freezer it gets down to room temp. The instructions say this meter is most accurate at 68 degrees, so that's what I did. A few of my readings may have been around 72 or so, but most of them I tested at 68. It was 4.6 every time. My tap water read around 7.0 and my RO water reading was 6.0...so I know the meter is doing something and not just stuck on 4.6. My new calibration solution should be in any day now. I'm planning on brewing another batch soon also. We will see what happens. Thanks again!

The difference in pH between a solution at 68 °F and 72 °F would be tiny. I think you are right about having a meter that is somehow off.

To check your meter, try taking the pH of some known solutions. For example, most finished (non-sour) beers are in the pH 4.0-4.4 range. (Shake the sample to decarbonate it before taking a reading.) You could also try taking the pH of wine. Whites are usually 3.0-3.3 and reds are usually 3.3-3.5. Likewise, the pH of Coca Cola is 2.5.


Chris Colby
Editor
beerandwinejournal.com