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Mashed out cracked corn, malted barley, and rye. Didn't want to use sugar so was careful with the temps. I mixed in yeast from a previous ferment 6 months ago and enough liquid that it could be called "sour mash". I got an SG of 1.060 and a starting pH somewhere near 5.5 (my meter is crap and I hadn't calibrated it so I can't swear to that pH). After 6 days ferment it is still bubbling, SG is 1.025 but pH dropped way down to 3.27. I recalibrated the meter and it still read 3.27. Tastes more sour than I remember in other batches. I'm not super-worried, even if it is Lactic acid it should be fine if it isn't contaminated with other stuff...It still needs longer fermentation though and I'm worried it may stall do to low pH. Does this seem OK? I've never bothered with pH with other ferments, but I've been fooling with these meters trying to calibrate them so thought I'd check it.

PossumPie wrote: ↑Sun May 18, 2025 12:11 pm
After 6 days ferment it is still bubbling, SG is 1.025 but pH dropped way down to 3.27. I recalibrated the meter and it still read 3.27. Tastes more sour than I remember in other batches. I'm not super-worried, even if it is Lactic acid it should be fine if it isn't contaminated with other stuff...It still needs longer fermentation though and I'm worried it may stall do to low pH. Does this seem OK? I've never bothered with pH with other ferments, but I've been fooling with these meters trying to calibrate them so thought I'd check it.

Ph sounds a little low. Out of curiosity are you using a refractometer or hydrometer to measure the SG?

Hydrometer. I can raise the pH with calcium carbonate. When I was teaching nutrition, a student who's husband worked for a Calcium carbonate mine gave me a large chunk to use as a visual aid in class. I boil it, and use it sometimes to slowly raise pH...

Give it a try CC will raise the pH.
If I were using corn and barley malt, I'd use the backset to lower the corns pH during cooking then add Calcium to raise the pH to 5.2 for mashing. The alpha enzymes in malt works better with some calcium.

https://brewingforward.com/wiki/Calcium

shadylane wrote: ↑Sun May 18, 2025 4:45 pm Give it a try CC will raise the pH.
If I were using corn and barley malt, I'd use the backset to lower the corns pH during cooking then add Calcium to raise the pH to 5.2 for mashing. The alpha enzymes in malt works better with some calcium.

https://brewingforward.com/wiki/Calcium

Thanks. I put the CC in a BIAB and lowered it into the fermentor. Later today I'll check the pH. It slowed down faster than I anticipated and the SG is still higher than I want it. I always keep backsets to add to a thumper or into the spirit run but never thought of it to modify pH. Makes sense. I think I'll check pH at various steps to see what's happening. I generally don't even bother with my pH meter.

Sounds like your water lacks buffering capacity.
You should fix that before you mash.

Before the days of pH meters I figure there's a reason distillers bragged about having limestone water for mashing.
Now days they use RO water and add what's needed.

As to backset, I only use it to acidifying corn when making a sour mash, so the starch breaks down better.
Then adjust the pH back up to what's needed for mashing before adding the malt.
Lowering then raising the pH makes the pH remain more constant during fermentation and the spent yeast adds nutrients.
I think adding backset to the pot or thumper is taking steps backwards and isn't the way to make sour mash.

After 2 days with the C.C. added, the pH raised from 3.27 to 4.06. It's still fermenting slowly, SG was 1.025 two days ago, today 1.020. I'm hoping to get it to 1.01 but with the troubles I've had, I'll be happy for anything under 1.020. It is a bit chilly, so I wrapped the fermentors in my heat mat and raised the temp from 65 F to about 71 F. That may help also.
My water buffers fine. I have well water that is alkaline and contains calcium.