Stuck Fermentations

[CCrisfield]

Hi everyone,

I’m fairly new to brewing and I’m having some problems with stuck fermentations. I brewed 4 batches of beer this month and all of them seem to be stuck! I’m wondering if anyone has any ideas of what I can do to fix my problem. I have to move at the end of the month and I was hoping to have everything bottled before moving. I’m not sure if there is anything I can do to fix these before I move or if I’m going to have to toss everything.
I brewed a milk stout (my first all grain batch) that is currently stuck around 1.040 and I also brewed a triple batch of raspberry ale (extract) which I divided into 3 small carboys so I could do some experimenting. I added some Belgian yeast to one, did my usual recipe with another and diluted the third with some water to make a lighter beer. These 3 are stuck at 1.017-1.026.

Here are some more details. I hope it’s not too much but I just want to give the whole story:

Beers:

Raspberry ale (extract) using Golden Light LME and some specialty grains.
Boiled 11 gallons in keg (90 minutes), cooled to pitching temp (75F) and aerated well.

I then added 4 gallons to one carboy (OG 1.068) and pitched 1 vial WLP575 (Belgain style ale yeast blend) (should attenuate around 80% so should finish around 1.013) without a starter. I added 4 gallons (OG 1.068)to another carboy and pitched 11 grams (1 pack) of rehydrated Danstar Nottingham ale yeast (should also attenuate around 80% and finish around 1.013). Finally I added 3 gallons to the last carboy and diluted with another gallon of water giving an OG of 1.049 (should finish around 1.010). This carboy also got 1 pack of rehydrated Nottingham.

I went to bed after brewing and fermentation had started in all 3 carboys when I woke up the next morning. The Belgian yeast wasn’t too vigorous, but the krausen filled the 1 gallon headspace and moved into the airlock on the beer pitched with Nottingham.

These beers were allowed to ferment at around 64-72F for a week. Most of the airlock activity had stopped at this point. These were then transferred into secondaries which contained 2-3lbs of previously frozen raspberries (not washed or pasturzed). The 2 bigger beers were given raspberries that I picked and the lighter beer was given store bought frozen raspberries. The beer bubbled very slowly for a day or two before airlock activity stopped. SG was taken 1 week after transfer to secondary and it was at 1.027, 1.026 and 1.018 for the beer containing Belgain yeast, undiluted with Nottingham and diluted with Nottingham beers respectively.

At this point I assumed that the fermentation was stuck so I moved it to a warmer location (75F) and gently rocked the beer. I know this is a higher than ideal temperature but I was in a hurry to get this stuff bottled. The next day there was no airlock activity in any of the beers so I stirred all of the trub and settled yeast back into the beer and held the temperature constant at 75F. After another day I took a SG reading and none of the values had changed.

I then went to a new store (as I suspected that maybe the first store had some old yeast) and bought some more dry yeast. I sprinkled 1 pack of US-05 into the Belgian beer, 1 pack of Nottingham into the undiluted Nottingham beer, and 1 pack of US-05 into the diluted Nottingham beer (no rehydration). Additionally I added ¼ teaspoon of diammonium phosphate (yeast nutrient) and 4oz of dextrose to each carboy as I thought it might give the yeast some nutrients and simple sugars to get started.

After adding the yeast, sugar and nutrient, slow airlock activity resumed for a day or two. I then measured the SG after 3 days and it was still the same (or in the case of the diluted beer it had gone up a point)! I am starting to get frantic as I have to move in 4 days and with ~1 gallon of head space in each carboy I think they would get pretty aerated on the 2 hour drive to the new place. I could maybe leave the beers with a friend and deal with it later but that still involves moving the beer around a lot.

I am also having a similar problem with the milk stout I brewed (5 gal). I mashed for 90 minutes at 152F and added 1.1lb lactose. The OG was 1.072 and the current gravity is 1.040. Assuming 1.042ppg from lactose, lactose should be contributing approximately 9 points to the OG and FG (as it is unfermentable). I originally added 2 packs of US-05 and added another pack of Nottingham after 3 weeks when warming and stirring did not work (yeast was added at the same time I added yeast to the raspberry beer). It was originally fermented at 64-72F but has also recently been warmed to 75F to promote fermentation.

I’m wondering if the water could be lacking something the yeast needs (my water is very low in minerals here, basically RO water) or if I just need to pitch more healthy yeast or what.

I assume there is also some unfermentable sugars in the raspberries but surely there aren't that many.

I was thinking that maybe there was some pesticide or something on the raspberries that was killing the yeast but I used store bought raspberries on one batch and hand picked raspberries for the other two. This also doesn't account for why the milk stout isn't attenuating as expected.

I’m using a keggle that I just made and while I think I cleaned it fairly well could there be some chemical or something that got into the beer that is killing the yeast?

Would it be a bad idea to bottle these? I'm assuming that they are all too high but what about the diluted raspberry beer that is at 1.017?

Also, I have checked my hydrometer with another and it is calibrated correctly.

Any suggestions would be hugely appreciated, sorry for the very long post!

 

[Fennis]

You stated that you are fermenting anywhere from 64F-72F. So are you fermenting in a place that experiences that kind of a temperature swing on a consistent basis? Do you have a place that is a little more stable in temperature to ferment? I know those temperatures are in ideal ranges for most ale yeasts, but if you are changing that much in ambient temperature throughout the day, that could be one reason why as you will get much better results of your ambient temp is somewhere in that ideal range, but also not changing.

Have you considered making starters? It will help significantly to create a starter and get that yeast really growing and happy before you pitch it. It sounds like you are compensating for batch size or gravity and ensuring you have enough yeast, but it might help to give them a boost and make a starter which will really get your fermentation moving.

Also, are you ensuring your yeast is at the proper temperature when you pitch it? For dry yeast that would mean pitching it around room temperature, and for liquid, whatever it states on the vial/package? If you are just pitching the yeast as soon as you take it out of the fridge, that could be a reason why there is a problem.

In the past with some kits, I've used yeast nutrients. I don't really know if they make a difference or not, all I noticed is it might shave off a few hours from the yeast really kicking off on fermenting.

Is your water from a well or is it treated city/town water? It might not hurt on your next batch to get some bottled RO water and see if that makes any difference.

 

[duboman]

To begin, it's difficult to analyze all the recipes at one time but a couple things stand out:

1 week primary is just not enough time and if you are consistently racking the beer off the yeast after 7 days then you are really not allowing enough time to ensure final gravity. 10 days to two weeks is better

You assume that because you checked one hydrometer against another that they are both correct but you did not check to see if they read 1.000 in distilled water at its calibrated temperature so conceivably they may both off

Fermentation temperatures should not have swings and this was not clear. If you want to ferment a beer at 62 then it should be at 62, not somewhere between 62 and 70 on any given day-once yeast start working they like stability through active fermentation, some like a gentle rise as they finish.

Some Belgian strains are very slow to finish and like it hot towards the end. They start off like a beast and then take forever to finish, again one week on yeast is just not ideal.

Starters (for liquid strains) and proper pitching temperature are necessary with yeast. Underpitching creates stress which can lead to poor attenuation.

All in all you need to work on your process (maybe recipes as well) to ensure you are getting the type of beer and proper finish you are trying to achieve.

 

[Pie_Man]

Dude, no offense, but that's a novel, most people don't want to read that much.

Let me first focus on potential causes of stuck fermentations:
- Wort fermentability: Extracts are notorious for not fermenting out like they should. I had this issue with a couple of batches then I switched to AG.
- Tranferring to secondary too early: If you remove the beer from the majority of the yeast too soon, you will likely have an under attenuated beer. Consider giving your beer 2-3 weeks in the primary. Many people, myself included, don't even bother with a secondary.
- Underpitching yeast: Consider making starters and using online pitching calculators like yeastcalc and mrmalty.
- Aeration: Lack of oxygen prior to fermentation can cause issues with yeast health and cell growth.
- Temperature during fermentation: Try to keep fermentation temps relatively stable. Flucuations up and down and fermenting too hot/cold can cause yeast to quit before they should.
- Equipment failure: Perhaps your hydrometer is off the mark. It's probably unlikely, but you may want to calibrate it with distilled water.

As far as what to do now. Adding more yeast rarely works, and usually introduces oxygen into the beer post fermentation causing oxidation. If the beer tastes good, I would bottle it. If it's too cloying, thick, and/or sweet for your taste, you can try experimenting with Brett which will consume most of the sugars that beer yeast could not. That's a longer term commitment and you might not want to do that with your upcoming move. There's always the sink drain; life's too short to drink bad beer.

 

[wikki]

- Wort fermentability: Extracts are notorious for not fermenting out like they should. I had this issue with a couple of batches then I switched to AG.

I think I had the same problem on the first batch that I made. The OG was 1.045 and it got down to about 1.018, but according to the instructions it should have been closer to 1.010. I left it in the primary for about 2.5 weeks and the gravity hadn't moved in several days.

Is there anything you can do about this? Is it even a problem? Was it close enough? I probably had similar problems as the poster. Temperature fluctuations weren't quite as extreme, but were probably a little higher than recommended.

 

[Pie_Man]

I think I had the same problem on the first batch that I made. The OG was 1.045 and it got down to about 1.018, but according to the instructions it should have been closer to 1.010. I left it in the primary for about 2.5 weeks and the gravity hadn't moved in several days.

Is there anything you can do about this? Is it even a problem? Was it close enough? I probably had similar problems as the poster. Temperature fluctuations weren't quite as extreme, but were probably a little higher than recommended.

In my opinion, if it tastes pretty good, I would bottle it. Adding extra yeast doesn't normally work without also oxidizing the beer and often doesn't work at all and causes oxidation. So let taste be your guide and learn for the next beer. Others might say you can add more yeast, but I disagree, not after 2.5 weeks. Some will tell you to rouse the fermenter that rarely works, but you're welcome to try.

 

[CCrisfield]

Thanks for all the replies! It sounds like there are lots of things to consider and things I may have done wrong.

1 week primary is just not enough time and if you are consistently racking the beer off the yeast after 7 days then you are really not allowing enough time to ensure final gravity. 10 days to two weeks is better.

It looks like I should have kept the beer in the primary for longer, I think this may be one of the main causes of all of my troubles with the raspberry beers. I transferred off the trub when I added the raspberries and didn’t want to wait too long and have no yeast to ferment the sugar in the berries. Should I maybe just add the berries to the primary next time? Additionally, the stout is still in it’s primary and it’s stuck too, so I guess this isn’t my only problem.

You assume that because you checked one hydrometer against another that they are both correct but you did not check to see if they read 1.000 in distilled water at its calibrated temperature so conceivably they may both off.

I have confirmed that they are accurate using distilled water. The beers also taste pretty sweet and usually the raspberries lose all their color and sink (as the sugars are eaten and the beer becomes less dense they seem to sink) but they are still fairly red and floating.

Is your water from a well or is it treated city/town water? It might not hurt on your next batch to get some bottled RO water and see if that makes any difference.

I’m using town water from Vancouver, BC. I haven’t heard of anyone around here having any troubles with the water but it is something I will look into.

You stated that you are fermenting anywhere from 64F-72F. So are you fermenting in a place that experiences that kind of a temperature swing on a consistent basis? Do you have a place that is a little more stable in temperature to ferment? I know those temperatures are in ideal ranges for most ale yeasts, but if you are changing that much in ambient temperature throughout the day, that could be one reason why as you will get much better results of your ambient temp is somewhere in that ideal range, but also not changing.

The beer was initially pitched at 62 but allowed to rise slowly over the week. I don’t think the temperature could have fluctuated more than 2 degrees or so in a given day but it could have. I don’t have a very precise way of controlling my temperatures right now but I’ll be figuring something out once I move.

potential causes of stuck fermentations:
- Wort fermentability: Extracts are notorious for not fermenting out like they should. I had this issue with a couple of batches then I switched to AG.
- Underpitching yeast: Consider making starters and using online pitching calculators like yeastcalc and mrmalty.
- Aeration: Lack of oxygen prior to fermentation can cause issues with yeast health and cell growth.

I guess wort fermentability could be an issue for the raspberry beers, but the stout was AG. The stout was also pitched with 2 packs of US-05. From what I have read they don’t really recommend starters for dry yeast and 2 packets was the recommended pitching rate. Underpitching is a likely cause for the raspberry beers though.

As far as what to do now. Adding more yeast rarely works, and usually introduces oxygen into the beer post fermentation causing oxidation. If the beer tastes good, I would bottle it. If it's too cloying, thick, and/or sweet for your taste, you can try experimenting with Brett which will consume most of the sugars that beer yeast could not. That's a longer term commitment and you might not want to do that with your upcoming move. There's always the sink drain; life's too short to drink bad beer.

Yeah it looks like that might be the only option seeing as I don’t have much time left to fix these. It makes me sad to dump it as I had a lot of time and money invested in these. Oh well I guess it’s a good lesson. I have since built a stir plate and temperature controller so hopefully these will help avoid stuck fermentations in the future.

Sorry Pie Man for another novel. There's just so many issues to address I can't help myself!

 

[Pie_Man]

For your next batch, I would suggest a fairly simple all grain recipe; limit the use of unfermentables and crystal malts. Make sure your thermometer is accurate as mash temperature also affects wort fermentability. Use a pitching rate calculator. Aerate the wort. Use your new temp controller to control fermentation temp (not ambient temp) and see what happens. It sounds like you have different causes for the under attenuation between batches.

 

[CCrisfield]

Thanks Pie Man,

I think I've got lots of things to work on for the next batch. I was thinking of trying a SMASH beer which should hopefully keep things simple for fermentation.

Now I just have one other question. Do you think it is worth keeping the beer? I don't have time to fix the problem before I move but I could just bottle it. I don't mind the effort involved in bottling but is a beer at 1.026 still going to be drinkable? Could I call it a dessert beer? Or is it going to be way too sweet?

Also, if I do bottle it should I be using plastic bottles to prevent bottle bombs or do you think it is unlikely that fermentation is going to restart. I'd prefer to use glass as I have no plastic handy but I could go and buy some.

 

[CCrisfield]

I've figured it out!! I recently bought a refractometer but in the interest of being concise I did not mention that I have been taking my measurements with it. What I did not realise is that once there is alcohol present in the wort it throws off the reading. I used some distilled water to calibrate the refractometer and I also used a sugar solution to measure it against a hydrometer (and both readings were the same), but I didn't ever use the hydrometer with the beer.

After reading this post: https://www.homebrewtalk.com/f163/3-stuck-fermentations-row-325721/index3.html I was directed to this website to calculate the actual final gravity: http://onebeer.net/refractometer.shtml

While the calculation on the website didn't turn out to be 100% accurate, I just took a gravity reading on one of my beers and it is shows 1.026 with the refractometer but 1.011 with my hydrometer.

That makes me feel much better! I am quite happy I didn't throw it out. I was so confused why all 4 of the carboys were refusing to ferment. Looks like I heated them up a fair bit unnecessarily but hopefully that shouldn't affect the
taste too much.

Looks like I will be bottling today after all!

 

[Fennis]

That is great news! Bottle away and enjoy all your hard work.

 

[Pie_Man]

Now I just have one other question. Do you think it is worth keeping the beer? I don't have time to fix the problem before I move but I could just bottle it. I don't mind the effort involved in bottling but is a beer at 1.026 still going to be drinkable? Could I call it a dessert beer? Or is it going to be way too sweet?

Also, if I do bottle it should I be using plastic bottles to prevent bottle bombs or do you think it is unlikely that fermentation is going to restart. I'd prefer to use glass as I have no plastic handy but I could go and buy some.

It really depends on the flavor. If you think it's drinkable, it really doesn't matter what the OG is. You can always blend the beer with other beers/beverages, cook/marinade with it, or just drink it. It's entirely up to you.

Hmm, good question about bottling. I would probably bottle in glass and keep the beers in a rubbermaid bin, which is good practice in general. I have a feeling wort fermentability is the main culprit, but I could be wrong.