Author Topic: major difficulties hitting target mash ph  (Read 350 times)

Offline mlogan

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major difficulties hitting target mash ph
« on: April 30, 2018, 08:43:12 PM »
Long time lurker, first time poster here.

I've been wanting to get a bit more serious about my water chemistry, so I recently had a water analysis done by Ward Labs, and also bought a Milwaukee MW-102 ph meter. This weekend was my first time taking ph measurements while brewing, and I had some really confusing results.

Here's the short summary of what happened: I used Bru'n water with my Ward Labs results as inputs to calculate various amendments. After doing so, I measured the ph of my mash water and found it was waaaay lower than predicted. (about ~3.6). I used baking soda to get back into the 5.4-5.5 range, and then mashed. I took a sample from my mash tun at about 20 minutes, cooled it to around 70F, and measured its ph at 6.5 which seems insanely too high.

So, it seems that basically everything went wrong here, hoping someone can help me figure out what. Following are all the various details about my inputs and process:

Measurements:
- This was the first use of the meter: I calibrated the ph meter using the 7.01 and 4.01 solutions provided with the instrument.
- I took all ph readings at close to room temperature (between 60 and 80), using the meter's temperature probe and temperature correction capability.

Brewing:
- Grain bill: 8lbs Munich malt, 1lb Vienna, 0.5lb Carapils.
- Mash: No-sparge, 150F, mash volume 8.25 gallons

Water:
- Tap water as analyzed by ward labs: Ca 30/Mg 10/Na 33/SO4 48/Cl 24/HCO3 110, PH: 8.4
- Amendments (for 8.25 gallons): 1.2 grams Gypsum, 7.0 ml lactic acid (88%).
- Target Profile: Ca 50/Mg 1/Na 5/SO4 57/Cl 43/HCO3 30
- Bru'n water predicted profile after amendments: Ca 39/Mg 10/Na 33/SO4 70/Cl 24/HCO3 -44.
- Bru'n water predicted mash PH: 5.4
- (If you're wondering why I didn't use Calcium Chloride instead of Epsum salt, which would have gotten me closer to the target, its because I didn't have any.)

Brew day results - as I explained briefly before, here's what went wrong on the brew day:
- After amending the water, I got a PH reading of about 3.6 which was obviously way way lower than the target.
- Adjusted back to a more reasonable PH by adding baking soda and stirring thoroughly. I added a total of 1.35 grams in small increments until the water got back to about 5.6
- Mashed in, took a sample after 20 minutes, let it cool to roughly room temperature and measured the ph at 6.5.

Anybody have any idea what I did wrong? Regarding the high mash ph, I supposed maybe I didn't wait long enough for the baking soda to dissolve, and thus it was still raising the ph after my final measurement. However, that doesn't explain how I undershot the ph by so much in the first place.

Thanks!

Offline EnkAMania

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Re: major difficulties hitting target mash ph
« Reply #1 on: April 30, 2018, 08:48:03 PM »
The ph value Bru'n Water is looking for is the mash after 15-20 minutes.  If I'm understanding, you took ph of the water and added baking soda.
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Offline mlogan

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Re: major difficulties hitting target mash ph
« Reply #2 on: April 30, 2018, 08:51:54 PM »
That's correct, however, my understanding is that malt naturally _lowers_ ph when mashed, and so I thought that I would have to start off higher than, or at least in the neighborhood of the target ph. Am I wrong there?

Offline denny

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Re: major difficulties hitting target mash ph
« Reply #3 on: April 30, 2018, 09:02:12 PM »
That's correct, however, my understanding is that malt naturally _lowers_ ph when mashed, and so I thought that I would have to start off higher than, or at least in the neighborhood of the target ph. Am I wrong there?

Yeah, you are.  You need to target mash pH, which is why Bru'nwater asks for your grist bill.
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Offline mlogan

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Re: major difficulties hitting target mash ph
« Reply #4 on: April 30, 2018, 11:57:00 PM »
I understand that the water ph is not what bru'n water is targeting. What I'm asking is, will addition of malt *raise* the ph of water? That's what would be required for my 3.6 ph to end up in the normal mashing range. My understanding is that its the opposite though - malt *lowers* ph. Indeed, if I remove grain from my grain bill in bru'n water, my estimated mash ph goes up, not down.

Offline Robert

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Re: major difficulties hitting target mash ph
« Reply #5 on: May 01, 2018, 12:07:24 AM »
Forget about the pH of the water. It's irrelevant.  The only thing you care about is the room temperature pH of the mash, and this is a product of the composition of the grist and the mineral ions in the water (not the pH of the water.)  If you input the grist and the water composition to Bru'n Water, it will give you said mash pH.  Repeat, forget that water even has a pH of its own.  It's irrelevant.
Rob
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Offline mabrungard

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Re: major difficulties hitting target mash ph
« Reply #6 on: May 01, 2018, 12:29:35 AM »
Yes, malt is a huge buffer. It will RAISE the pH of the combined water and grain when combined in a mash.

Yes, the pH of your water was probably quite low prior to the addition of the grains. Adding the baking soda completely defeated the chemistry of the mash and its no surprise that the resulting wort was high. I'm sorry that your lesson was so painful.

PS: as several have already mentioned, THE pH OF THE WATER IS IRRELEVANT. The object of your water adjustments is to produce a system that has a proper wort pH.
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