Homebrewing - Beer, Mead, Wine, Cider @sopuli.xyz Aarkon @feddit.de 6 mo. ago

Stuck fermentation?

First off: Sorry for the link, apparently I can't upload images at the moment.

This is my first ride with a wireless hydrometer, so maybe this is just me not being used to having access to gravity readings all the time, having become a bit obsessed with the numbers. Looking at Brewfather on the other hand though, my gravity really hasn't changed for like 36 hours now, before reaching its estimated final value. Now I'm afraid that my fermentation has stalled, and as the gravity was never really high to begin with, I fear being stuck with something not only low in low in alcohol but also tasting thin & weak. This is supposed to be a "Klosterbier" (not a real beer style, but closest described as some sort of brown ale), with which I'd have preferred to err on the stronger side rather than on the weaker.

The main reason for the low initial gravity I believe is too little boil off: While pre-boil gravity was OK (Brewfather predicted 1.039, refractometer gave me 1.037, might even be considered to be within measuring tolerance), the post boil reading should have been 1.051 but was only 1.041.

After boiling, I took around half a liter of wort, chilled it down in a mason jar and added dry yeast, agitating it every now and then. The next day, I pitched now very agile yeast into the main bucket and fermentation started out perfectly. The ups and downs in the graph may just be results of krausen and/or condensate dripping back onto the RAPT pill or creating ripples in the wort surface.
Now, I'm really asking myself what went wrong. I don't think I caught myself any infection, the bucket was properly sanitized as well as the collection vessel & I was very careful handling all of it. The yeast also very happily ripped through the major parts of the sugars, so I don't think it's a yeast issue either. My grain bill looks as follows:

2.25 kg (50%) — BESTMALZ BEST Munich — Grain — 15 EBC
2.21 kg (49.1%) — The Swaen Swaen Vienna — Grain — 10 EBC
40 g (0.9%) — Weyermann Carafa Special II — Grain — 1100 EBC

The performed mashing steps:

Mash In — 38 °C
Protein Rest — 50 °C — 40 min
Beta Rest — 63 °C — 30 min
Alpha Rest — 72 °C — 30 min
Mash Out — 78 °C

I'm not sure what to do, or if I should do anything at all. I can live with the beer having 3.5% ABV like it has now probably. My storage is dark and reasonably hygienic, so I don't think I have to elongate the beer's shelf life that way. The alcohol might then even overpower the taste of the grains if I added table sugar or anything for another percent of alcohol.
What I'm slightly concerned with though is overwhelming hop aroma because there apparently is not that much dissolved sugar to counteract the bitterness.
Any suggestions?

24 comments

Are you fermenting under pressure? If so your final gravity will be off by quite a bit using a gyro based meter. The absorbed co2 will give you a false reading. I use mine more to determine when fermentation has stopped and I can bottle. Maybe take a sample and measure with a normal hydrometer and see if your reading is correct.
- No pressure, just a plain plastic bucket. I'd be happy enough to know if my fermentation really stopped, it just seems way too early with just roughly one day of activity.
I had to deal with this issue few months ago.

Stopped fermentation was caused by fluctuating temperature and too quick cooling after pitching the yeasts.

We salvaged it to sellable beer but it wasn't great.

Give it a taste test and proceed as normal brew, in a best case scenario you will have sweeter beer.

Restarting a fermentation is tricky and unreliable so I wouldn't do it. You may have issues with carbonation so it may end up flat or, if you can, force carbonate it.

Try to find what caused it, so you don't have to deal with it in the future. I can't tell what it is from your post - yeasts, temperature, bad measurements...

I don't see anything obvious so that's it, I don't have experience with this hydrometer so I can't help with that (bad calibration or some issue there).

Tldr: not much to do now, try to find out what caused it for future brews.
- The temperature fluctuated from 20.2 to 17.7° C in 10 hours. I don't know, is that much? Doesn't look too bad for me, but I'm not yeast. :D
  
  No it isn't bad or large fluctuation, in our case it got to 15 C and then stopped at about 6 or 7 °Bx (~1,025 SG) and get to about 10C afterwards.
  
  US04's or other ale strains are pretty tolerant to "small" fluctuations or don't getting the temperature right.
For everyone involved and/or curious: I took a regular hydrometer reading last evening, which gave me ~1.011/1.010. So while not too far off, that is still significantly lower than what the Pill sees. Also, when taking some more time to observe, I realized that there is indeed still airlock activity going on. Now that I was sure there was still CO2 being produced, I then peeked under the lid and saw that the Pill had collected quite some dried trub on its waterline. After seriously sanitizing everything, I took it out, cleaned it and pitched it back, though that didn't result in more realistic measurements. So I guess it's down to a calibration issue.
What a stupid situation: The only at least halfway reliable measuring instrument after fermentation start remains the saccharometer, which requires a sample of 100 - 200 ml for each measurement, so you can't do this every day for an elongated period of time without losing significant amounts of product for a batch if this size. Only alternative would be a transparent fermenter like the FermZilla and leave the saccharometer afloat the whole time. Not sure if I like that idea.

At least I got a taste sample this way and I'm happy to report that there is nothing weird going on. It's not the biggest beer in the world, but summer is coming anyway, so that's only a half bad thing. I'll report back with pictures in a few weeks after conditioning. Cheers!

@SpiderShoeCult@sopuli.xyz @plactagonic@sopuli.xyz @waldek@lemmy.86thumbs.net @drre@feddit.de
- uh thanks for the update! I'm happy your beer is coming along nicely. personally I wouldn't bother with hydrometer readings during fermentation. it sure is nice to see the numbers change but i find airlock activity to be just as good. i take a final reading after bubbling has stopped (only because I'm curious, never used the value for anything), and call it a day. anyways cheers!
  
  I have my fermenter exposed to rather significant temperature deltas, so airlock activity maybe is not the best indicator in my case as the air inside expands and contracts. It would suffice of course just to measure daily with the refractometer to see if there still is activity. Not having to though is a tempting idea to me. 😄
- You may try refractometer with correction and then using hydrometer before bottling/when you need exact measurements. Other options are too expensive for homebrewers, like in our brewery we use device from AntonPaar that uses about 10ml per measurement. It costs about 5-10 times more than the pill.
What is your brewing setup? I've used your grain quantities in BeerSmith with a Braumeister 20L setup for the out of the box efficiency (without stirring the malt during mashing or a finer grind or extra boiling) and it gave me a post-boil of 1.042, which seems to fit with your result so I'd guess you had an efficiency issue. How did the mashing go?

I've noticed that when boiling for the standard 1 hour, I get about a 10% increase in gravity (for the digits after the 1 - that is, pre-boil of 1.064 leads to post-boil of 1.070 ish), so in your case 1.037 to 1.041 would check out for me.

For my brewing setup, 30 minutes at 63C doesn't really cut it, I've tried it and noticed 60 minutes or even 90 minutes work way better. But then I mostly use kveik and the indication seems to be for longer mash times (something about it being unable to digest sugars made of 3+ units).

I'm not sure I get your last point. If your FG is higher than expected, you should reasonably have more sugars left over from fermentation, so more residual sweetness.

Regardless, I'd suggest RDWHAHB, and see what you get out of this. Do share your final results, I am curious what it's like.

Out of lazyness, I just let all my beers sit in the fermenter for 2 weeks and that seems to work out just fine. Some finish bubbling after 2 days, some after 12.

Edited to add: just noticed from your yeast link, you also use an all-in-one system, does it suffer from the same low efficiency issues as the Braumeister, I wonder?
- I've got a BrewZilla Gen 4 35L. I don't know what you'd consider low efficiency, but the unit's default profile in Brewfather is ~76%, whereas the software calculated roughly 65% efficiency for the batch in question. I've got no idea though how that compares to the Braumeister 20L other than the values in Brewfather are rather similar.
  What was a first was crushing the grains myself, but mashing on itself went fine. Looking back, I might have wanted to check for starch with iodine, which I even had available. Might do next time. I also might want to add though that I used 13.5 liters of strike water and did what from my understanding is a batch sparge (raising & draining the mash tun, then adding hot water from a second vessel with a jug) with another 15 liters at 80° C. Not perfect for efficiency, I know, but as described my pre-boil gravity was fine. I must just have been to shy on the heat while boiling.
  
  In the back of my head, I have the number of 10% boiloff being desirable, which would match with your 1 hour boil observation.
  
  My last point is that I'm afraid the beer might be too thin as in too much liquid for too few sugars dissolved in it. I didn't boil off enough water, so I did not concentrate the wort far enough to reach the desired post boil gravity.
  
  The software calculated efficiency for the Braumeister is spot on for me if just using it like set it and forget it, so about 65%. I can up that with stopping the pump during mashing, opening the thing and stirring the mash about once every 30 minutes in my 90 min mash. Also by milling the malt a bit finer. But too fine, and I get a stuck mash. With this, I managed around 75, or how much the software sets as standard for pot and cooler method, so I'm happy with that.
  
  I also start the brew with 23ish liters of strike water, dump 6 kg of malt in there and sparge with 5-6 liters at 80C. Boil 1 hr and end up with 18-19 liters in the fermenter with the rest full of trub in the Braumeister (2-3 liters maybe?) I never measured how much is left and I can sparge with 4 or 6L. I just eyeball it according to how much wort is in when I lift the malt pipe.
  
  In your case, I'd say maybe the mash did not go very well.
  
  I wouldn't be too worried about the body. It could be that your fermentation just stopped a bit higher because all that's left is longer sugars, unfermentable, but good for the body. One way to find out...
any indication of airlock activity? did you taste it? (never used a wireless hydrometer: did it become stuck somehow, bubbles stuck to it may cause it to float, giving readings which are too high)
- Airlock activity is so little that it might as well be expanding air (the bucket sits in my garage without extra heating or cooling, subject to the temperature cycles visible in the graph). There is nothing really in the bucket the hydrometer could be stuck against on my opinion, but I‘d have to open it to check - which I’m reluctant to do because of infection risk, obviously.
  
  Taste testing I didn’t think of until now, good thinking. Will do tomorrow. If it’s completely dry, the calculations must be way off. If there is still sugar in it, I assume it's non-fermentable stuff. I always forget if that's maltose or dextrose.
So this is how we ended up. It’s a little thin as expected, but drinkable. Also it has become a little sweeter than anticipated, with some hop coming through. Had a commercial Kellerbier the other day and it was like this "done right". Head is obviously good, its stability Ok.
All in all, it works surprisingly well as a summer beer.

The secondary fermentation stalled as well, I had to shake the keg seriously in order for the yeast to carbonate and consume the priming sugar. So maybe my yeast just was a little weak to begin with.
- Congrats you made drinkable beer. At least it wasn't complete loss.
  
  Bad yeasts is pretty easy issue to solve so good luck on your next brews.
  
  I had made a starter (took a mason jar of wort after the boil, chilled it and pitched my yeast into it while the rest of the wort chilled overnight) and it went off really quickly, I had the impression it was all well.
  
  But hell, maybe it really dropped out of solution faster than I thought. It's somewhat clear (the stuff on the glass is co2 bubbles), even though I'm neither filtering nor storing it cool and only take from the keg what I'm about to drink that evening and put that in a fridge.
Take an actual gravity sample with degassed beer using a hydrometer. Your RAPT pill may have krausen crud stuck to it throwing off the reading. My conclusion for these sorts of devices is that they're useful for monitoring temp and letting you know when your fermentation is completed but the measurement of FG is probably inaccurate.
- I'll try agitating the beer a little to see if that sets anything free. It will sit in the bucket for at at least two more days anyway, so I'm not afraid of trub. If that doesn't help, I'll also take a look at the hydrometer, thanks for the suggestion.

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