Post Boil Wort PH High

Hey guys. I just brewed my Oktoberfest. (well technically its a 6C Dunkle Bock based on 2014 BJCP) My issue is with post boil PH. My mash was 5.32, pre boil 5.33, and post boil 6.12.

Preboil vol of 15.4g, 1.047, post boil 11.75, 1.063.
I calibrated my meter at 7, 4, and 10 before use today.

I read in another thread that adjelange commented on, that a good post boil target is 5-5.2. I know thats not a rule, but what caused mine to be so high, and what can I do about it in the future?

This HAS to be there reason Ive had beers not attenuate out fully.

All help is appreciated.

Thanks!

calebstringer said:

Hey guys. I just brewed my Oktoberfest. (well technically its a 6C Dunkle Bock based on 2014 BJCP) My issue is with post boil PH. My mash was 5.32, pre boil 5.33, and post boil 6.12.

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That's a bit of a WTF? There is no reason that this should happen so I suspect a problem with the pH meter. If it doesn't turn out to be that I am mystified. Go back and measure the pH of the buffers. They should, obviously, be 4 and 7.

calebstringer said:

Preboil vol of 15.4g, 1.047, post boil 11.75, 1.063.
I calibrated my meter at 7, 4, and 10 before use today.

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There is no need to do the calibration with 10 buffer unless you are reading pH's between 7 and 10. You may actually be better off reading things up to say 8 and perhaps a bit beyond with a cal done with 4 and 7 buffers as 10 buffers have to be watched carefully. They pick up CO2 from the atmosphere and go off fairly fast.

calebstringer said:

I read in another thread that adjelange commented on, that a good post boil target is 5-5.2. I know thats not a rule, but what caused mine to be so high, and what can I do about it in the future?

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It is plenty strange that it went up at all. That's why I suspect the pH reading.

Checked ph meter against calibration solution... dead on.

Re-calibrated, pulled new sample from fermenter (no yeast pitched yet) hit 6.07 ph. Very close to my original reading....

Im clueless.

OH, and I checked it w/ the calibration solution I have been using, and a sealed, new 7.0

Did you, at any point, try and adjust your pH by adding alkali to the mash (especially slow-to-dissolve chalk)? What all did you add between the mash and end of the boil?

This defies chemistry, so something is going on here if that is in fact a good reading.

The good news is you are taking pH readings along the way. This is an excellent way to learn about the process.

My recipe is:
9 lbs vienna
7 lbs pilsner
6 lbs munich
1.5 lb caramunich
1.5 lb caravienne
1.5 lb melanoiden
All weyermann malts

74% Mash Eff
72.7% BH Eff

Bru'n Water gave me an estimated Mash Ph of 5.5 with:
Mash water 2.3g Gypsum, 3.1g Calcium Chloried, 3 ml Lactic

I need a new water report because the last couple batches I have come in exactly .15 ph lower than Bru'n Water. Previously i would hit it dead on. So I took that into account w/ my water adjustment, as I was targeting around 5.3

Sparge: 1.7g gypsum, 2.6 Calcium Chloride, 3.8 ml lactic

75 min mash, with a mash out of 170, held for 10 min.
90 min boil, 5 min whirlpool

Thanks for the input guys.

ajdelange said:

as 10 buffers have to be watched carefully. They pick up CO2 from the atmosphere and go off fairly fast.

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Timely as I was just wondering about the stability of the buffers in this regard.

calebstringer said:

Checked ph meter against calibration solution... dead on.

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And these werw new (freshly made or just opened) calibration solutions?

snowveil said:

Im clueless.

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Me too. That's why I'm asking what may seem like stupid questions.

GotPushrods said:

Did you, at any point, try and adjust your pH by adding alkali to the mash (especially slow-to-dissolve chalk)?

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Chalk is a good call. That would explain it....

calebstringer said:

I need a new water report because the last couple batches I have come in exactly .15 ph lower than Bru'n Water. Previously i would hit it dead on. So I took that into account w/ my water adjustment, as I was targeting around 5.3

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I'm not saying you don't need a new water report but the differences you are seeing may well be caused by differences between the actual malts you are using and the malt parameters assumed by the program.

ajdelange said:

And these werw new (freshly made or just opened) calibration solutions?




Me too. That's why I'm asking what may seem like stupid questions.

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My primary calibration solution isn't very old. Only used once. However I did have a sealed bottle of new 7.0 that I opened and it tested the same

And my reading was taken at room temperature

Any other thoughts/ideas?

Well either the pH is really going up which is inexplicable chemically or it is going don but the meter is reading higher which, given that it passes cal checks, is also inexplicable.

For the pH to rise something has to be absorbing protons. This would have to be calcium phosphate or calcium carbonate which got carried over into the kettle. Was the sparge runoff bright?

If it is something with the meter it would have to be a loose wire or chip connection or something blocking the junction or coating on the bulb. Which model meter is it and how old is it?

ajdelange said:

Well either the pH is really going up which is inexplicable chemically or it is going don but the meter is reading higher which, given that it passes cal checks, is also inexplicable.

For the pH to rise something has to be absorbing protons. This would have to be calcium phosphate or calcium carbonate which got carried over into the kettle. Was the sparge runoff bright?

If it is something with the meter it would have to be a loose wire or chip connection or something blocking the junction or coating on the bulb. Which model meter is it and how old is it?

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Can you please define what you mean by bright sparge runoff?

The meter is a Milwaukee MW102. It is less than a year old, and the sensor probe is five weeks old (I accidentally left the original one out of storage solution)

As ajdelange said in his first post here, there's no need to use the 10 buffer. So if you didn't know that and calibrated in numerical sequence using the 4.0, then 7.0, then 10.0, your meter would probably just be programmed to be calibrated between 7 and 10, which would give you funky inaccurate results, so maybe re-calibrate with only the 4 and 7, then stability test the buffers, and then retest.

calebstringer said:

Can you please define what you mean by bright sparge runoff?

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I'm obviously grasping at straws here but if there were some undissolved calcium phosphate in the runoff the runoff wouldn't be bright - the solid material would render it hazy.

calebstringer said:

The meter is a Milwaukee MW102. It is less than a year old, and the sensor probe is five weeks old (I accidentally left the original one out of storage solution)

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Again grasping at straws here. Still possible that an intermittancy is responsible for a funny reading but most unlikely given that things are relatively new and that the cal check is being passed.