Adjusted ph in the fermenter just after pitch. Mistake?

Hello all,
I just made a 6 gal batch of a Rochefort 8 ‘clone’. My mash ph was 5.6 about 15 minutes in, and I didn’t think much of it since dark beers should drop in ph during the mash. But only immediately after pitching did I remember that it’s the roast malts at work and there are only 2 ounces of Carafa in this recipe. A quick ph check at that point revealed a ph of 5.7. After poking around a bit I concluded that it may have been due to the 3 total ounces of hop pellets in the boil preventing the ph from dropping (not sure of the validity of this). I also saw that the post boil ph of dark beers ‘should’ be no more than 5.4. So in a moment of panic I added 15 ml of 10% phosphoric to the fermenter, rocked it around to mix, and rechecked ph. Another round, and 2 hours later, the ph was 5.41. I then questioned whether I should have done that :roll_eyes:. So the question is, did I harm the yeast by doing that? I know if I am going to adjust ph post boil I should do it post boil. Also, is it correct to assume that the boiling hops prevented the ph drop?

I think you did alright, assuming the initial 5.4 was correct. Not sure why it stayed at 5.4. Don’t add any more of course. But I’m sure all will be just fine.

I don’t think the kettle hops had anything to do with pH

Thanks Dave,
To be clear, the initial mash ph was 5.6, the ph after pitching was 5.7. I added the acid just after pitching to drop it to 5.4.
BTW the fermentation was roaring about 10 hours after pitching, so early results are encouraging.

Thanks Denny.

Sorry, I must have mis-read your initial post. So OK, it went from 5.6 in the mash, to 5.7 after the boil, to 5.4 after adding acid after the pitch.

This all seems extremely odd to me. It seems like your pH meter or method is not calibrated. Dark beers should have low pH, and post-boil should be lower than the mash, not higher. All seems very odd indeed. Check calibration.

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Thanks Dave,
Seemed very odd to me too and the only thing I could dig up was possibly the boiling hops, but I think Denny feels that’s not a thing. I calibrate the meter each time I use it, and if things seem to be going awry I replace the probe, which I did within the last year. My cal solution is not old either. I have performed several smell tests since adding acid, including.

  • ph in the fermenter has dropped to about 4 roughly 48 hours in.
  • ph of an oatmeal stout I have on tap is 4.5.
  • ph of a Dubbel I have on tap is about 4.2 (this one seems a tad low to me though).
  • ph of my tap water is about 7.4 which is consistent with prior readings
  • ph of some Brother Thelonious I drank was about 4.25

That all seems to indicate that nothing is off with the meter. I did not expect the Dubbel to be as low as it is, but I was also able to raise a pint to 4.5 by dissolving a very small amount of pickling lime in a very small of water and adding it to the pint.

I could replace the probe but I hate to discard a probe that isn’t at end of life.

It does sound like your pH meter is just fine, all readings as expected, with exception for your fermenting batch. I guess the yeast took care of the high pH if it’s now in the low 4’s as expected, so everything might turn out just fine?! I hope so. Good luck. We might just never understand why the pH was what it was, but like I say, the yeast takes care of it so hopefully all fine in the end anyway.

Thanks Dave,

Yup the yeast definitely dropped the ph, What I will never know is what it would have done had I not panicked and dosed the batch with phosphoric. As you said, might never know. Have to wait and see how it turns out.
Safe to conclude that the acid addition to the wort immediately after pitching did not harm the yeast since the fermentation was roaring 8 hours after pitch.
I love to brew and I am frequently amused at the puzzles I create for myself in the process :smile:
Thanks again.

Hi again Dave,

For posterity, I believe I figured out the source of the high ph post boil. Fermax. Did some noodling on what else could have caused this, and some grepping around, and found someone on another forum indicating that DAP raises ph. Checked for myself, and sure enough the Fermax jacked up the ph in tap water.
I typically use a tablespoon of Fermax in a 5 gallon batch, added with whirlfloc with 15 minutes left in the boil. FWIW I have never been able to find anything definitive on the dosage or the timing, 1 tsp for 5 gallons or 1 tsp per gallon, add to the boil or add to the primary.
The same thread indicated that the ph increase does not affect the final ph of the finished beer. What I am seeing seems consistent with this assertion.
So as you said above, all fine in the end. I suppose I’ll have to taste the finished beer to see if it has any sourness to it and adjust.

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Ah, now that makes perfect sense. I’m glad you figured it out. Indeed, some yeast nutrients are slightly alkaline, which explains everything. Personally, I don’t think yeast nutrient is needed for beer. It is only essential for mead, and optional for cider and wine. But beer/grain/wort contains all the essential nutrients that yeast needs, with exception of zinc, which only comes into play IF you will be repitching the same yeast to many batches, otherwise the yeast will be fine without extra zinc for several batches. So I would skip the nutrient next time – in this case it has only led to a mystery which has fortunately been solved! It doesn’t really hurt to add nutrient in beer, but it doesn’t really help anything either IMHO.

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Good advice, thanks for all the input.

Thanks Dave. You got me re-thinking about using yeast nutrient. I have always used it in beer batches for the zinc, but may give up on it except for a tiny bit (basically a pinch) that I use when making starters with DME. I always thought that traditionally a bit of extra help for the yeast was good, but now…

Seems like an over reaction.

Hi Denny,
What exactly is it that you feel might be an over reaction?

Discontinuing the use of yeast nutrients

we use phosphoric to acid wash yeast at work (production brewery) so you’re probably good, at worst it will kill off the weakest yeast and/or any wild things developing

Hi all,
Thanks for the replies. I thought I would close this out by sharing the outcome.
I believe it was definitely the Fermax and the unfortunate timing of a ph reading after pitching that caused me to question what went wrong. When fermentation completed it was 3.95. I read somewhere that a higher final ph would bring out more malt flavors. At 3.95 ph the gravity sample tasted weak/thin to me, and of course the beer was only a few days old. Managed to raise the ph to 4.23 after the addition of about 1/4 tsp of lime dissolved in water that was boiled then cooled. To my untrained palate I think it helped the malt flavors but that could be confirmation bias.
Nevertheless I can’t detect any off flavors, the fermentation was vigorous and fast. The batch is a BDS so it will be some time before I sample the matured and carbonated beer. So far though, no blood, no foul. Lesson learned.

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