Missed Mash pH on last three brews

[natmartin]

I’ve used Bru’n Water for several years now. It’s always worked pretty well for me, and my measured pH has always been pretty close to what the program estimates. However, my last few batches have ended up pretty far from the estimate, and I was wondering if any of you could help me figure out what’s going on. I’ll give as many details as I can to help to figure this out.

• I’m measuring pH using a Thermoworks 8689. I don’t calibrate every single time, but I calibrated between the first and second batches I’m mentioning, and it didn’t have to change much with the recal. (So it seems to hold calibration pretty well.)
• I always measure pH at room temperature, or a little below. I pull a sample, and chill it down inside a cocktail shaker sitting in an ice bath. If I wait too long, it can get down to ~50F, but usually I measure around 60F or 70F.
• I take pH measurements every 10 minutes during the mash
• I’m using SF Bay Area tap water, filtered through a carbon filter, treated with Sodium Metabisulfite (might be Potassium? I’d have to check at home) for Chloramine. When I take water samples for testing, I always run it through the carbon filter for a direct comparison. I always run the filter at a trickle to collect water. It's typically very soft water.
• I've tested my water both using home lab kits and ward labs.
• I’m using Brew in A Bag methods, no-sparge. So I’m treating my full volume of strike water.
• I measure acid additions using a 10ml graduated cylinder
• I measure mineral additions using a high-accuracy gram scale, which I check with a 100g weight for accuracy.
• I typically add mineral additions and acid to the strike water before adding grains.
• I store my acid in the fridge.
• Batch 1:
  • Style: Pre-Prohibition Lager
  • Grist: 70% 6-row, 25% Red Malted Corn, 5% Flaked Rice
  • Water tested using BruLab kit
  • Water treated with no mineral additions, 6.39ml of 88% Lactic Acid
  • Predicted pH: 5.24
  • Measured pH: 5.85
• Batch 2:
  • Style: Porter
  • Grist: 70% Crisp Marris Otter, 10% Crystal 75, 5.6% White Wheat, 5.6% Chocolate Malt, 1.8% Carafe Special III, 1.8% Crystal 120, 5.6% Flaked Rice
  • Water tested using BruLab kit
  • Water treated with 0.58g salt, 2.1g Gypsum, .34g Calcium Chloride. No acid additions
  • Predicted pH: 5.43
  • Measured pH: 5.95
• Batch 3:
  • Style: Cold IPA
  • Grist: 75% Pilsner Malt, 25% White Malted Corn
  • Water tested using Ward Labs
  • Water treated with 3.5g Gypsum, 1.94g Calcium Chloride, 3.77ml of 88% Lactic Acid
  • Predicted pH: 5.35
  • Measured pH: 6.08 (!)

Any thoughts? I'll be brewing again this weekend. I'll calibrate my pH meter the night before, and check it on the day-of.

 

[dmtaylor]

This seems very odd. There seems to be something wrong with your calibration method or lack thereof, or you have a bad probe. Ensure you are calibrating with good standard solutions (4.01, 7.01, etc.). You might need new standard solutions, or a new probe.

 

[VikeMan]

I agree with @dmtaylor. Unless the cal solutions are brand spanking new and never before opened, that's the first thing I'd be looking at.

 

[natmartin]

The calibration solutions are/were brand new, purchased from Thermoworks along with the meter.

 

[VikeMan]

The calibration solutions are/were brand new, purchased from Thermoworks along with the meter.

Did you check the dates on the solutions?

 

[natmartin]

Did you check the dates on the solutions?

Yup. Doesn’t expire for a year.

 

[CleanEmUpIves]

What does EZWater, Mash Made Easy, Brewers Friend, Beer Smith, etc... tell you?

The various mash pH prediction methods give different results and can be like playing the lottery.

 

[natmartin]

What does EZWater, Mash Made Easy, Brewers Friend, Beer Smith, etc... tell you?

The various mash pH prediction methods give different results and can be like playing the lottery.

I haven’t checked them, since bru’n water has always worked great before. I can try those.

 

[VikeMan]

Yup. Doesn’t expire for a year.

That makes bad cal solution less likely, but not impossible.

And unless you have very alkaline water, I kind of doubt this is a mash pH model issue.

It might help if you could post your source water profile, plus the full grain bill (including weights) and water volume for one of those batches.

Another thought, although it probably has nothing to do with your issue... That pH 10.0 buffer doesn't seem to be full. You shouldn't need a 10.0 buffer, since everything you'll measure (in a mash) will be below 7.0.

 

[natmartin]

That makes bad cal solution less likely, but not impossible.

And unless you have very alkaline water, I kind of doubt this is a mash pH model issue.

It might help if you could post your source water profile, plus the full grain bill (including weights) and water volume for one of those batches.

Another thought, although it probably has nothing to do with your issue... That pH 10.0 buffer doesn't seem to be full. You shouldn't need a 10.0 buffer, since everything you'll measure (in a mash) will be below 7.0.

Ok, when I cal this weekend, I'll just do a 2-point. I also have cal solutions from morebeer, so I can actually check with both just to be share.

I'll gladly share everything I've got. I'll use the Cold IPA recipe, since that was most recent, used a ward labs report, and is what I'm re-brewing this weekend.

Water report:

• Calcium (CA): 11.4ppm
• Magnesium (Mg): 4.0ppm
• Sodium (Na): 15.0ppm
• Bicarbonate (HCO3): 62.0ppm
• Carbonate (CO3): 1.0ppm
• Sulfate (SO4): 18.0ppm
• Chloride (Cl): 10ppm
• Total Alkalinity: 51.0ppm
• Water pH: 7.9

Grain bill:

• 4.5kg Mecca Grade "Pelton" Pilsner Malt, SRM 1.8
• 1.5kg Sugar Creek White Malted Corn, SRM 2.98

Strike Water: 26.2L
Water treated with 3.5g Gypsum, 1.94g Calcium Chloride, 3.77ml of 88% Lactic Acid

 

[natmartin]

What does EZWater, Mash Made Easy, Brewers Friend, Beer Smith, etc... tell you?

The various mash pH prediction methods give different results and can be like playing the lottery.

EZWater with the same inputs estimated 5.51pH. Bru'n water estimated 5.35. Both very far off from my measured 6.08.
(Note, both estimate 5.74 pH if I left out the acid)

 

[CleanEmUpIves]

I haven’t checked them, since bru’n water has always worked great before. I can try those.

Mash pH prediction software works for those who don't own a pH meter.

In lieu of making a test mash and/or knowing the DI pH / acidity (buffering capacity) of all malts involved it's basically a guessing game.

https://oldfashionbrewery.files.wor...ive-on-mash-ph-i-the-grain-bill-d-m-riffe.pdf
I'd be interested to know the DI pH / acidity (buffering capacity) of the Malted Corn.

 

[VikeMan]

Ok, when I cal this weekend, I'll just do a 2-point. I also have cal solutions from morebeer, so I can actually check with both just to be share.

I'll gladly share everything I've got. I'll use the Cold IPA recipe, since that was most recent, used a ward labs report, and is what I'm re-brewing this weekend.

Water report:

• Calcium (CA): 11.4ppm
• Magnesium (Mg): 4.0ppm
• Sodium (Na): 15.0ppm
• Bicarbonate (HCO3): 62.0ppm
• Carbonate (CO3): 1.0ppm
• Sulfate (SO4): 18.0ppm
• Chloride (Cl): 10ppm
• Total Alkalinity: 51.0ppm
• Water pH: 7.9

Grain bill:

• 4.5kg Mecca Grade "Pelton" Pilsner Malt, SRM 1.8
• 1.5kg Sugar Creek White Malted Corn, SRM 2.98

Strike Water: 26.2L
Water treated with 3.5g Gypsum, 1.94g Calcium Chloride, 3.77ml of 88% Lactic Acid

In BrewCipher, I'm getting 5.42 for this recipe. I had to specify flaked corn, but if anything, malted corn ought to drive pH a little lower than flaked corn, at least that has been my experience with raw/flaked vs. malted versions of other grains.

 

[natmartin]

Mash pH prediction software works for those who don't own a pH meter.

In lieu of making a test mash and/or knowing the DI pH / acidity of all malts involved it's basically a guessing game.

https://oldfashionbrewery.files.wor...ive-on-mash-ph-i-the-grain-bill-d-m-riffe.pdf
I'd be interested to know the DI pH / acidity of the Malted Corn.

When I say it worked for me before, I mean that it always lined up with my measured pH within a reasonable error bar.

I also wonder if the malted Corn threw off the prediction. But that wouldn't explain the Porter recipe, which was all conventional grains.

 

[natmartin]

In BrewCipher, I'm getting 5.42 for this recipe.

Cool, so estimates are between 5.35 - 5.5, all very reasonable. And all way off from the measured >6pH. At least I didn't do something totally crazy with the additions....

 

[CleanEmUpIves]

If you're taking pH measurements every 10 mins, how long into the mash are you comparing your measurements with the predictions?

 

[natmartin]

If you're taking pH measurements every 10 mins, how long into the mash are you comparing your measurements with the predictions?

6.08 is somewhat of an average. Here's the exact measurements:
10 minutes: 6.04
20 minutes: 6.06
30 minutes: 6.10
60 minutes: 6.35

The porter:
10 minutes: 5.82
20 minutes: 5.82
30 minutes: 5.82
40 minutes: 5.94
50 minutes: 5.92
60 minutes: 5.91

I typically see the pH increase slightly during the mash.

Same pattern with Batch 1, first sample 5.48, last sample 5.85

 

[CleanEmUpIves]

Do you do a full BruLab kit on your water right before each brew session or are you using the same test results for each brew?

Did the tap water composition recently change? More/less rain/snow in the area, water company switched wells, etc...

 

[natmartin]

Do you do a full BruLab kit on your water right before each brew session or are you using the same test results for each brew?

Did the tap water composition recently change? More/less rain/snow in the area, water company switched wells, etc...

I do a new BruLab kit whenever my TDS changes significantly. I'm in the SF Bay Area, so our drought means that water sources are changing a lot. But it's usually pretty soft.

However, Batch 3 was brewed 6 days after I took the sample for Ward Labs, and the TDS measurement on the brew day matched what I measured when I took the sample. So the chances of a big change in water supply is low.

 

[VikeMan]

So the chances of a big change in water supply is low.

And you'd need a pretty dang big change to cause the kind of pH difference that you're seeing. This doesn't seem to be a model issue, and I highly doubt that it's an issue of water changing. You'd need some pretty unusual water (very alkaline, but very low calcium and magnesium) to get what you're measuring with that grist and those additions.

 

[natmartin]

And you'd need a pretty dang big change to cause the kind of pH difference that you're seeing. This doesn't seem to be a model issue, and I highly doubt that it's an issue of water changing. You'd need some pretty unusual water (very alkaline, but very low calcium and magnesium) to get what you're measuring with that grist and those additions.

Yeah, exactly. That's why I brought this problem to the smart people here! It's stumped my homebrew club too.

Measurement error still seems like the most likely answer. I have an older Milwaukee meter still, so I'll check with both meters this weekend (and calibrate both too)

Does acid storage matter at all? Does keeping it in the fridge change anything?

 

[CleanEmUpIves]

Were your previous calibrations also 3 point?

Looks like the solutions you have are not the NIST recommended values in the manual for that meter so the calibrating point would have to be adjusted.

Is the probe clean?

 

[natmartin]

Were your previous calibrations also 3 point?

Looks like the solutions you have are not the NIST recommended values in the manual for that meter so the calibrating point would have to be adjusted.

Is the probe clean?

I've always done 3-point. I can switch to 2-point. Yeah, it's weird that the solutions that Thermoworks sells don't match what they have in their manual. So I manually enter the solution values. There's no temperature curve printed on the label, so I've been using the printed value. But I do calibrate pretty close to room temperature, so I doubt that's a major source of error.

I believe the probe is clean. Since I bought it, it's only been stored with storage solution, and I rinse with distilled water before and after every use (by dunking in a glass of distilled water)

 

[CleanEmUpIves]

How many brews have you done with 3 point that were good?

 

[natmartin]

How many brews have you done with 3 point that were good?

Four batches earlier in the year, using this probe, with the 3-point cal, were within expected error margin of Bru'n lab measurements. The problems have been only on the most recent three batches.

 

[VikeMan]

Does acid storage matter at all? Does keeping it in the fridge change anything?

Lactic acid should be good for at least a few years. I suspect fridge storage probably won't make much difference, but if anything it might help a little.

 

[dmtaylor]

Does acid storage matter at all? Does keeping it in the fridge change anything?

I'm not sure. Personally I wouldn't refrigerate it.

Your 10.01 point might be messing up the pH curve.

It's that, or your probe.

 

[Silver_Is_Money]

Ok, when I cal this weekend, I'll just do a 2-point. I also have cal solutions from morebeer, so I can actually check with both just to be share.

I'll gladly share everything I've got. I'll use the Cold IPA recipe, since that was most recent, used a ward labs report, and is what I'm re-brewing this weekend.

Water report:

• Calcium (CA): 11.4ppm
• Magnesium (Mg): 4.0ppm
• Sodium (Na): 15.0ppm
• Bicarbonate (HCO3): 62.0ppm
• Carbonate (CO3): 1.0ppm
• Sulfate (SO4): 18.0ppm
• Chloride (Cl): 10ppm
• Total Alkalinity: 51.0ppm
• Water pH: 7.9

Grain bill:

• 4.5kg Mecca Grade "Pelton" Pilsner Malt, SRM 1.8
• 1.5kg Sugar Creek White Malted Corn, SRM 2.98

Strike Water: 26.2L
Water treated with 3.5g Gypsum, 1.94g Calcium Chloride, 3.77ml of 88% Lactic Acid

For the recipe I've attached here I get a mash pH of 5.54 after adding the 3.77 mL of 88% Lactic Acid. And 5.87 mash pH before adding the 3.77 mL of 88% Lactic Acid.

 

[SanPancho]

on water report look for upper San Leandro reservoir data. its Medium alkalinity, not soft. Not sure if that explains it all but it’s fairly significant difference vs straight tuolumne water source.

 

[natmartin]

on water report look for upper San Leandro reservoir data. its Medium alkalinity, not soft. Not sure if that explains it all but it’s fairly significant difference vs straight tuolumne water source.

Yeah, but I'm using direct lab tests from samples at my house, not EBMUD water reports. Certainly there are differences when they switch reservoirs, but I don't think big enough to cause this.