Is this Stuck Fermentation?

[landmissle]

Hi all,

I'm a brand new home brewer and working on my 2nd batch. My first was a extract kit that I purchased from MoreBeer! and was an American Red Ale. It was so much better than I was expecting for my first beer! I'm totally hooked.

I came across a clone recipe for St. Stan's Red Sky Ale and being from Modesto ( where St. Stan's was founded) and as a lover of Red Ales, I had to try it. I purchased this extract kit from Austin Home Brew (AHB). I performed a full boil using six (s) gallons of water and the brew day seemed to go well. AHB recommended SafeAle S-33 yeast for this recipe, which I used. The yeast kicked in about eight (8) hours later and was creating lots of bubbles in the airlock for about two (2) days. I slowed down significantly after that. At least based on airlock bubbles.

My fermzilla carboy is somewhat temperature controlled in basically a big insulated keg jacket/enclosure. I keep the temps moderated with frozen gallon and half gallon water containers. I've been able to keep the temps between 64 and 68 degrees F. I've let the temp move upwards more towards 68 degrees F the last two days.

The recipe indicated that OG would be 1.057, but my reading was 1.051 before pitching the yeast. I took my next specific gravity reading eight days after brew day and it read 1.020. Four (4) days later I took another reading and it was still at 1.020. I was hoping to bottle my batch this weekend, assuming the specific gravity was stable, but the current reading is significantly higher than the predicted FG of 1.013.

I'm concerned that my OG and current and potential FG are off a fair amount from the predicted recipe numbers. Of course I'll take another specific gravity this weekend, but I'm concerned it will still be 1.020.

Would this be considered a stalled fermentation and if so, is there anything I can do?

I've read about stirring the batch or agitating it, but then I've read that's not good to do as it will introduce oxygen into the beer. I read you could add more yeast and a few other things, but I don't know if any of these ideas are appropriate and if, indeed, do I have a case of stalled fermentation.

Any suggestions would really be appreciated!

 

[passedpawn]

Unusual to have a stuck fermentation with extract. Stirring/agitating is, in my opinion, ridiculous. Don't do it. 1.020 is not horrible, but 1.010 is much better for your beer and its drinkability, so go ahead and try a couple of things.

With what equipment are you measuring gravity?

Do this:

• Add more yeast. Just tear open another sachet of yeast and dump it into the fermentor. Do this immediately. S-33, S-04, S-05 are all fine dry yeasts for your purpose. If you go to the store to buy more yeast, also get some alpha amylase (most homebrew shops carry this).
• Wait a few days and see if the gravity changes. If it does not, add 2 teaspoons of the AA. Remove any temperature controls you have and let it go to room temperature. AA will take a couple of weeks to do its magic at room temp, but you should see your gravity come down to expected in that time.

 

[AlexKay]

I have had S-33 be very, very slow finishing up. I would give it another week and measure SG again. And then another week. Very slow.

 

[IslandLizard]

With what equipment are you measuring gravity?

That^ is an important question!
Before you do anything, let us know.

 

[DBhomebrew]

With what equipment are you measuring gravity?

Answer that before doing any of the following suggestions.

If you're using a refractometer and have not used a calculator that compares original and current gravities in observed Brix, your ferment is complete.

 

[landmissle]

Wow, thanks for all the replies! I'm using a hydrometer that came with the MoreBeer! Premium kit. I believe it is this one:

https://www.morebeer.com/products/beer-wine-hydrometer-correction-scale.html

 

[passedpawn]

Wow, thanks for all the replies! I'm using a hydrometer that came with the MoreBeer! Premium kit. I believe it is this one:

https://www.morebeer.com/products/beer-wine-hydrometer-correction-scale.html

OK great.

Continue with my suggestions. Good luck.

 

[BrewnWKopperKat]

(@landmissle, over many years, people have occasionally reported problems very similar to yours.)

I agree with @AlexKay, give it time.

Also, depending on the style/flavor/brand/freshness/.. of the "extract", with S-33 yeast, the beer may be at a stable final gravity. S-33 can leave a lot of the complex sugars behind (see the orange and dark red bars).

eta: SG 57, FG (est)13 is 77% AA; which seems high for S-33. at 70% AA, the estimated FG would be 17.

 

[seatazzz]

Another suggestion, try calibrating your hydrometer. This can be done with plain water, at the temperature noted on your hydrometer. If it comes out a few points higher or lower than 1.00, adjust your beer reading from there. They have been known to be off a few points. And I also agree with the above, give it some more time.

 

[GoodTruble]

As suggested above, it is a good idea to check your hydrometer in plain water just to make sure it is accurate.

If it really is 1.020, I agree with giving it another week. And I agree with removing temperature control at this point and letting the temp rise.

 

[mac_1103]

SG 57, FG (est)13 is 77% AA; which seems high for S-33.

Yeah, S-33 won't do that. One of the other recommended strains just barely might. But if the OG really was 1.051, then it's sitting at around 61% AA right now. So it should go a few more points eventually.

 

[landmissle]

Hi all,

I've ordered some more S-33 yeast. It should be here on Saturday. I really don't have a local brew store close to me, so it's either an online purchase or a 45 + mile out-of-town-trip for me. The latter would have to wait till Saturday anyway due to work.

I checked the hydrometer. At 76 degrees F it was reading about .099 maybe .098 from the tap. I then measured chilled water from refrigerator with a temp of around 66 degrees F and it was right at 1.00.

@passedpawn, you mentioned I should add the yeast immediately. I don't have any S-33 on me right now. I should get it Saturday. I do have an extra packet of Cellar Science "Cali". That's obviously a totally different strain of yeast. Would it be better to wait Saturday or add something immediately?

Also, when I add the yeast, should I rehydrate it (I've done this on both batches) and should I swirl the beer around to help oxygenate the yeast. Or literally just drop it in and leave it alone?

Again, thank you for all the advice.

 

[jsphlynch]

• also get some alpha amylase (most homebrew shops carry this).
• Wait a few days and see if the gravity changes. If it does not, add 2 teaspoons of the AA. Remove any temperature controls you have and let it go to room temperature. AA will take a couple of weeks to do its magic at room temp, but you should see your gravity come down to expected in that time.

Since this was a moderate gravity extract batch, I'm going to respectfully disagree with the suggestion to use alpha amylase. The amylase will break longer unfermentable sugars into simple fermentable ones, but the extract manufacturers know their stuff and have already done a fine job of breaking down those sugars for you. There's plenty of stories on this site of people who added alpha amylase and had then had the yeast chew thru absolutely everything as the amylase broke down every long sugar it could get its hands on and refused to stop.

As mentioned above, S-33 leaves more residual sugar even when fully fermented, so it's expected to finish a bit on the high side, though I agree 1.020 sound particularly high if your OG measurement is accurate. I wonder if something messed up your OG reading so you were actually more around the expected OG. Nonetheless, things you can try:
-Raise the temp a bit. Not a lot, just into the low 70s.
-Rouse the yeast. If your fermenter is something you can give a little shake without opening it, go for it. I agree with your concern about oxygen if you stirred/shook it with the fermenter open.
-Add a yeast that can eat maltotriose, such as US-05.
-Taste it. Does it taste excessively sweet? If no, you're probably in pretty good shape.
-Wait longer. When in doubt about a fermentation, this is almost always a good idea.

 

[hotbeer]

If you haven't been opening the FV and letting air into it every time you take a sample for the FG, then you can leave your beer in the FV as long as you want. The longer you leave it the clearer it will get as all the stuff suspended in it fall to the bottom. When that happens, you can pretty much be assured that weeks earlier you reached the FG for that batch.

If you have to do something, then do as @passedpawn suggested. Or just assume it's done and bottle after it's been the total time the recipe said to leave it in the FV. Or wait for a longer time for it to clear up.

Whatever you do, don't be in a hurry to rush it to bottle just because fermentation is over. The yeast still do stuff even after they finished converting the sugars they wanted to alcohol.

 

[IslandLizard]

The only thing I don't see working is adding extra yeast at this point, especially the same one (S-33).
1 pouch should be enough for 5 gallons of 1.051 wort. There should be plenty of yeast already, 3-5 times the effective # of cells that were pitched.

A bit of rousing may help to resuspend the yeast, but just letting it be for another 2 (or even 3) weeks at slightly higher temps (68-72F) should finalize it.

Yeast that's already in the beer does NOT need oxygen anymore, it's long past her growth phase.

You did a full volume boil, which is usually not needed with extract brews. I doubt it would change the fermentability of the wort, but maybe @BrewnWKopperKat could shine some light on that.

A couple questions:
How did you rehydrate the yeast? Could that water have been too hot perhaps?
Could there have been a sudden temp drop? When the big fermentation event concluded is it possible the ice packs in the jacket/enclosure dropped the temps a bit too far? That could stall the fermentation.

That said, sometimes it happens. Most of us here have been exactly there, a stalled batch with no clear reason as to why.

 

[passedpawn]

The only thing I don't see working is adding extra yeast at this point, especially the same one (S-33).
1 pouch should be enough for 5 gallons of 1.051 wort. There should be plenty of yeast already, 3-5 times the effective # of cells that were pitched.

A bit of rousing may help to resuspend the yeast, but just letting it be for another 2 (or even 3) weeks at slightly higher temps (68-72F) should finalize it.

Yeast that's already in the beer does NOT need oxygen anymore, it's long past her growth phase.

You did a full volume boil, which is usually not needed with extract brews. I doubt it would change the fermentability of the wort, but maybe @BrewnWKopperKat could shine some light on that.

A couple questions:
How did you rehydrate the yeast? Could that water have been too hot perhaps?
Could there have been a sudden temp drop? When the big fermentation event concluded is it possible the ice packs in the jacket/enclosure dropped the temps a bit too far? That could stall the fermentation.

That said, sometimes it happens. Most of us here have been exactly there, a stalled batch with no clear reason as to why.

I've had bad yeast that failed to ferment properly. Notty, way back in the day when they were accidentally stamping holes in the pkg when adding date code. Old liquid yeast that must have had low viability. Anyway, adding a sachet of dry yeast has no downside and can positively rule out poor yeast health in the fermentor.

I agree with trying a different yeast.

IMO, rousing is a myth, a bit of personification of the yeast haha. I've added whole fruit into a beer and the yeast gladly chewed right through the skin and finished the beer without any sort of "rousing". I think the myth persists because people agitate a fermentor and see bubbles begin to rise and assume that's fermentation, which you know is just existing CO2 being release. Shake an open bottle of beer and see what happens.

 

[BrewnWKopperKat]

You did a full volume boil, which is usually not needed with extract brews. I doubt it would change the fermentability of the wort, but maybe @BrewnWKopperKat could shine some light on that.

I don't think that a full volume boil is a factor in the high FG.

Based on what I've read (How to Brew, 4e, Colby's content, Basic Brewing Radio, ...), with "session" and normal" strength beers, it appears that

• full volume boil with all extract at start of boil and
• partial boils (1/2 water & extract at start and rest at end)

are essentially the same.

 

[IslandLizard]

Anyway, adding a sachet of dry yeast has no downside and can positively rule out poor yeast health in the fermentor.

IMO, it has no upside either: it does nothing.
It won't resolve poor yeast health either, being a relatively small amount of dormant cells pitched into a hostile environment of relatively high ABV with no simple fermentables left.

Now if one were to make a starter with the yeast (S-N-S preferred) or better, a small batch, and 24-72 hours later pitch the actively fermenting starter or batch into the stalled one, there may be a chance to resurrect it. I'd probably add some glucose/dextrose along with it too.

 

[IslandLizard]

I don't think that a full volume boil is a factor in the high FG.

Based on what I've read (How to Brew, 4e, Colby's content, Basic Brewing Radio, ...), with "session" and normal" strength beers, it appears that

• full volume boil with all extract at start of boil and
• partial boils (1/2 water & extract at start and rest at end)

are essentially the same.

Thank you for confirming this!

So we're most likely back to this, then:

(@landmissle, over many years, people have occasionally reported problems very similar to yours.)

I agree with @AlexKay, give it time.

Also, depending on the style/flavor/brand/freshness/.. of the "extract", with S-33 yeast, the beer may be at a stable final gravity. S-33 can leave a lot of the complex sugars behind [...]

Or make a starter/small batch with the new yeast as I outlined in #18^, and pitch that into the stalled one and wait/see if it resurrects.
Nothing to lose, IMO.

 

[BrewnWKopperKat]

I don't have any S-33 on me right now. I should get it Saturday. I do have an extra packet of Cellar Science "Cali". That's obviously a totally different strain of yeast. Would it be better to wait Saturday or add something immediately?

Also, when I add the yeast, should I rehydrate it (I've done this on both batches) and should I swirl the beer around to help oxygenate the yeast.

Adding more S-33 probably won't get the beer to FG 13; US-05 might.

With either strain, pitching yeast into a mostly fermented wort will be stressful. Re-hydration may help. Making a starter with liquid yeast may help. A recent "Experimental Brewing Podcast" (179, 178?, 177?) offers insights into why, in common situations, making a start with dry yeast may be a really bad idea.

I checked the hydrometer. At 76 degrees F it was reading about .099 maybe .098 from the tap. I then measured chilled water from refrigerator with a temp of around 66 degrees F and it was right at 1.00.

Thanks for reporting back on this.

Actual water volumes and boil off rates can also be causes of the difference between recipe stated OG / FG and actual OG / FG.

And on rare occasion, I have seen where the recipe estimated OG was off by a gravity point or two - often do to slight differences in 'extract' PPG or assumptions about steeping (vs mashing) efficiency.

A combination of "slight differences" (water volume, ingredient PPG, steeping efficiency assumptions), all in the same direction, could result in estimated OG of 57 being measured OG of 51.

---

FWIW, if you do nothing, and if the FG remains stable at 20 over the next week, it should be safe to bottle.

 

[Brewer Mike]

One point to add - as someone else mentiond, hydrometers are calibrated at a particular temperature. If you measured 1.051 O.G. at, say 80 degrees, and your hydrometer is calibrated at 60, you'd actually have a O.G. of 10.53.
https://www.brewersfriend.com/hydrometer-temp/

 

[landmissle]

Hi all,

I decided to rouse the yeast and increase the temperature. Previoulsy the temp was occilating between 64 and 68 degrees F. Now it's 69 to 72 degrees F. I'm still using a little ice to keep it in that range.

I'm now seeing a little airlock activity. I took a specific gravity yesterday (three days since the last one) and it's dropped to 1.019 or 1.018. So raising the temp seems to have kicked up the activty a little.

A few folks indicated that I should remove all temp control. If I remove all the ice, I can keep the fermentation vessel at an ambient temperature of 75 degrees F. Would that be OK or would that be running a too warm?

I want to thank everyone again for all the input. This situation and the advice given has helped my understand the yeast attenuation percentage number and how that relates to ABV, OG and FG. Based on that, I see how using S-33 would likely not bring down an OG from 1.057 to a FG 1.013. Had, I known that I probably would have chosen one of the liquid yeasts that were recommended for the recipe. Both of which have slightly higher attention numbers.

Based on an average attentuation of 70%, I'm hoping I can get this batch down to 1.016 without adding additional yeast.

 

[VikeMan]

I decided to rouse the yeast and increase the temperature. Previoulsy the temp was occilating between 64 and 68 degrees F. Now it's 69 to 72 degrees F. I'm still using a little ice to keep it in that range.

I'm now seeing a little airlock activity. I took a specific gravity yesterday (three days since the last one) and it's dropped to 1.019 or 1.018. So raising the temp seems to have kicked up the activty a little.

Sometimes rousing the yeast causes some dissolved CO2 to come out of solution (and out the airlock) for a while. And increasing the temperature will decrease the hydrometer reading, due to a temperature driven change in density. (Did you correct the reading(s) for temperature?) I'm not saying that fermentation hasn't resumed, just that I couldn't swear to it based on the information provided.

 

[jsphlynch]

I'm now seeing a little airlock activity. I took a specific gravity yesterday (three days since the last one) and it's dropped to 1.019 or 1.018. So raising the temp seems to have kicked up the activty a little.

In addition to what @VikeMan said, CO2 is less soluble at higher temperatures, so raising the temp will lead to a bit of airlock activity even without yeast activity.

If I remove all the ice, I can keep the fermentation vessel at an ambient temperature of 75 degrees F. Would that be OK or would that be running a too warm?

I personally would have no concerns about raising the temp to constant 75 deg this late in fermentation.

Based on an average attentuation of 70%, I'm hoping I can get this batch down to 1.016 without adding additional yeast.

Don't get too carried away with chasing numbers. Let your taste buds be your guide. If taking a taste tells you something is undesirable, use the numbers to help understand what the underlying cause might be, but if it tastes good it doesn't matter if it tastes good at 1.018/1.019, 1.016, or 1.013.

 

[GoodTruble]

At this point, it is unlikely raising to 75F would matter. But if it's moving, maybe just wait it out.

 

[landmissle]

Hi all,

Vikeman and jsphlynch may have a point. The minimal airlock activity I'm seeing may be just a product of the increased temperate range and the temp ossilation that's occuring within that new range (viz. 68 to 73 degrees F).

I took another specific gravity reading yesterday (four days after the last and day 20 since start of fermintation) and the reading is still 1.019/18. From all the advice given I understand that S-33 can be slow, but how long it too long? I've heard that keeping the beer in the primary beyond a month can introduce off flavors from dead/dying yeast. We are at day 21 as of today. I've only brewed one batch before and I did not move that batch to a secondary fermentation vessle. I would like to do same thing here.

Regarding the taste of the samples. I'm no beer expert, but I would say it taste fine with a slight hint of apricote smell. Not sweet, but also a bit "thin". I'm not sure how else to express that latter component, maybe weak or diluted? At least for my expectations.

So, I'm still unsure where I should go from here. Wait another week for another specifc gravity measurement and then maybe bottle if no further movment? I could add some more yeast, like the recommended US-5, but I'm not sure if it's too late for that. If not, would adding this yeast impact the intended flavor of this clone-recipe (St. Stan's Red Sky Ale)?

So there's my update. I continue to reread this tread to absorb all the advice given and consider what I should do next. Thanks for all the help.

 

[DBhomebrew]

I would say it taste fine with a slight hint of apricote smell. Not sweet, but also a bit "thin".

Parroting some of the above...

That tells me the slightly elevated FG (compared to the recipe) doesn't need to be "fixed". 'A bit "thin"' means adding more yeast to reduce FG would only make it thinner. You likely don't want that.

Carbonation will help give it some perception of body.

Also, no harm in leaving a beer in primary for a while on the homebrew scale. Commercial large capacity fermenters are a different beast.

 

[mac_1103]

how long it too long? I've heard that keeping the beer in the primary beyond a month can introduce off flavors form dead/dying yeast. We are at day 21 as of today.

You heard wrong (mostly). I almost never leave one in the primary for less than 21 days unless I'm planning to bulk age for a very long time - as in months. Most likely your beer is done and will be good despite the fact that you missed your OG and FG by a few points. Another week before you package isn't going to hurt anything and will only help the beer clear.

 

[jsphlynch]

So, I'm still unsure where I should go from here. Wait another week for another specifc gravity measurement and then maybe bottle if no further movment?

Here's what my approach would be: since the gravity has been stable for an extended period of time and it tastes fine, I'd declare it to be done, bottle it up this weekend, and anxiously wait for it to carbonate so I can start putting it in my belly. Although it likely wouldn't hurt to give it another week, I'd be surprised if that dropped the gravity at all.

I could add some more yeast, like the recommended US-5, but I'm not sure if it's too late for that. If not, would adding this yeast impact the intended flavor of this clone-recipe (St. Stan's Red Sky Ale)?

Not too late, but I'm not sure there's much point to adding yeast at this point. Maybe it'll drop the gravity a couple more points, but if the beer's fine now, why bother with another intervention? And no, I wouldn't expect it to noticeably impact the flavor.

I've heard that keeping the beer in the primary beyond a month can introduce off flavors form dead/dying yeast. We are at day 21 as of today. I've only brewed one batch before and I did not move that batch to a secondary fermentation vessle.

I've heard that too, but never experienced it. My best guess is that people who experience yeast off-flavors after a month in the primary have other problems with yeast health that make them really susceptible to aging poorly (though I reiterate this is merely my guess). I would not use a secondary for your current beer even if you opt to let it rest longer.

Regarding the taste of the samples. I'm no beer expert, but I would say it taste fine with a slight hint of apricote smell. Not sweet, but also a bit "thin". I'm not sure how else to express that latter component, maybe weak or diluted? At least for my expectations.

A little stonefruit (such as apricot) is to be expected from that strain. As mentioned above, carbonation will help with the body.

 

[landmissle]

Hi all,

Ok, the stuck fermentation drama is now officially over. I took another specific gravity today and it was again 1.019/18. With the help of my daughter, into the bottles it went and can now forget about it.

I'll check-in, in about two or three weeks and let you know how it turned out. I'm really curious if this clone recipe will match my memory of what Red Sky Ale was like.

Again, thank you for all the feedback and advice. I do really appreciate it.

 

[landmissle]

Cracked open the first bottle yesterday. I have to say the recipe is pretty close to what I remember the beer being like. At an estimated 4.3 % ABV, its' a bit light on the alcohol compared to the original, but is very drinkable. I may try this again with a different yeast.