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Frank Trosset
04-29-2013, 12:14 PM
So Im having some problems with the PH creeping up as the fermentation cycle progresses.

I check OG and PH for each beer on a daily basis and am finding that the PH is doing exactly the opposite of what Id expect. Here is an example of the latest Kolsch I have brewed:

4/15/13 - (Yeast Pitched) OG 1.048 PH 5.2
4/19/13 - OG 1.020 PH 4.45
4/21/13 - OG 1.012 PH 4.7
4/25/13 - OG 1.012 PH 4.8
4/29/13 - OG 1.010 PH 4.77

I dump yeast from the cone till it runs clear every day that I have listed for checking the PH and Gravity.

The beer stays for two weeks in the fv at a steady temp at 62 F, then spends 1 week in gradual temp drop till it gets to 30 F

At that point it is transferred to a Brite and kegged.

Can anyone see any obvious flaws with this approach that could be leading to the problem Im having with the PH?

Any help or insight would be great, thanks!!

-Frank

jwalts
04-29-2013, 04:31 PM
Bamforth writes that pH rises slightly during the end of fermentation, but your rise seems a little excessive. The fact that your beer made it down to 4.45 tells me you're probably giving your yeast a reasonable amount of free amino nitrogen. Maybe WaterEng is onto something, but I'd expect water buffers to resist the initial pH drop (and result in a pitching pH above 5.2) instead of bringing it back up from a lower value.

Autolysis would cause your pH to rise, but it sounds like you're already paying attention to that. Kolsch yeasts flocculate pretty poorly, though. Did you dump yeast every day or only on the days you listed? If you dump your yeast rapidly, you could be drilling beer through the cone and not getting rid of yeast as effectively as you believe. Overpitching could also promote autolysis as your yeast culture gets older over time (less growth = less reproduction -> higher fraction of old vs. young cells).

Finally, is it possible that your pH meter drifted out of calibration?

Joe
Ale Asylum
Madison, WI

Frank Trosset
04-30-2013, 11:53 AM
What is your brewing water like and what treatments are you performing before or during brewing?

My tap water profile:

PH - 8.01
Calcium - 6.0 PPM
Magnesium - 2 PPM
Sodium - 11 PPM
Potassium - 0
Iron - 0
Bicarbonate - 32 PPM
Carbonate - 3 PPM
Sulfate - 9 PPM
Chloride - 4 PPM
Nitrate - 1.4 PPM

I do use Epsom Salt, Calcium Chloride, Chalk and Gypsum depending on the beer and water profile that Im going after. Im using 88% Lactic Acid in my sparge water as well.

For the Kolsch I used Gypsum, Calcium Chloride and Epsom salt in the Mash and Sparge water.

Frank Trosset
04-30-2013, 11:57 AM
Bamforth writes that pH rises slightly during the end of fermentation, but your rise seems a little excessive. The fact that your beer made it down to 4.45 tells me you're probably giving your yeast a reasonable amount of free amino nitrogen. Maybe WaterEng is onto something, but I'd expect water buffers to resist the initial pH drop (and result in a pitching pH above 5.2) instead of bringing it back up from a lower value.

Autolysis would cause your pH to rise, but it sounds like you're already paying attention to that. Kolsch yeasts flocculate pretty poorly, though. Did you dump yeast every day or only on the days you listed? If you dump your yeast rapidly, you could be drilling beer through the cone and not getting rid of yeast as effectively as you believe. Overpitching could also promote autolysis as your yeast culture gets older over time (less growth = less reproduction -> higher fraction of old vs. young cells).

Finally, is it possible that your pH meter drifted out of calibration?

Joe
Ale Asylum
Madison, WI

My initial thought was autolysis. So I started dumping yeast on a more regular schedule, however, I only dumped on the days listed in the initial post. And I do dump fairly rapidly, so you could be onto something with drilling the beer through the yeast cake. Ill try dumping slower and see if I get better results.

I check the meter every time I use it against my tap water to ensure Im getting consistent readings, so I believe it is accurate.

ChesterBrew
04-30-2013, 01:12 PM
I check the meter every time I use it against my tap water to ensure Im getting consistent readings, so I believe it is accurate.

Actually, you should be checking it against a buffered solution for accuracy. Tap water can vary... trust me.

Frank Trosset
04-30-2013, 02:08 PM
Actually, you should be checking it against a buffered solution for accuracy. Tap water can vary... trust me.

You are right! I had just checked against some buffed solution and found that the meter was off by .35! Yikes. So it appears that it has been drifting on me over the past couple weeks. Ill keep a closer eye on it and make sure that there is no other culprit.

Thanks everyone for the input!

tringali
04-30-2013, 09:09 PM
One other thing to consider, I get more consistent and accurate pH readings with my Hanna meter if I let the probe sit in whatever I'm testing for more than 15 min. before taking a measurement. If I try to take a reading just after immersing the probe, it can vary a little and is prone to drift.

ChesterBrew
05-01-2013, 05:37 AM
Also, measuring a pH meter against a heated sample (actual mash temp) will totally decrease its lifespan. Always measure against a cool sample.

jemthebrewer
05-15-2013, 10:15 AM
Agreed with some of the advice here...the SOP I used for measuring pH was a daily calibration (2 point at pH 4 and pH 7 is usually sufficient). Any time the instrument was turned off, I would recalibrate before taking a measurement. +1 at measuring pH only on room temperature samples. I would worry about leaving the probe in wort/beer for too long, as proteins can also foul the probe. Regular probe cleaning (not just rinsing) is also important.

Jim Matt
Head Brewer, Rhinegeist Brewery

Giada
10-15-2013, 09:01 AM
Very interesting thread.
I've noticed the same thing in my beers, but just the one that I dryhop during fermentation.
Do you think the hop can slightly increase the pH?

BostonianBrewer
03-30-2016, 02:34 PM
Very interesting thread.
I've noticed the same thing in my beers, but just the one that I dryhop during fermentation.
Do you think the hop can slightly increase the pH?

Yes hops will effect the ph and cause it to rise

Cellarman - boston ma