Slow fermentation... or is it?

DeniqueCoelum · Nov 8, 2024

Another newbie question (will they ever end?

) ... just wondering how slow is slow fermentation, and is this something I should be worried about? Pretty much all my brews have pretty rapid fermentation, and it's all done and dusted within 4-5 days of kick-off. This one seems to have slowed down and is just plodding along, albeit still making progress.

For reference, this is a 23L batch with WLP Monastery Ale Yeast, around 7.5kg of malt and a kilo of Belgian candi. This is the largest amount of malt I've ever used in one batch, and I wondered whether that might have something to do with the slow-down on the fermentation - too much sugar? Is that a thing?

Twostage · Nov 8, 2024

It’s still progressing. I’d just leave it alone and let it carry on.

Larse · Nov 8, 2024

Too much sugar isn't a thing, otherwise wine making wouldn't happen. To be fair though, some yeasts don't have very high alcohol tolerance (hence wine yeast), but that wouldn't be the case here.

There are likely some unfermantable sugars in there from crystal malts for example, but that would be intentional to add more body. This would be reflected in your expected FG.

It's not even been a week, your beer is likely to need two weeks minimum to finish out.

Stu's Brews · Nov 8, 2024

As other's have said, leave it for now. With a beer with such a high starting gravity I'd expect it to take a little longer to ferment out.

One question I do have is what quantity of yeast did you pitch? I would have used two packs of the WLP yeast for a beer with that starting gravity. If you used less then it may result in a slower than desired fermentation.

DeniqueCoelum · Nov 8, 2024

Stu's Brews said:
As other's have said, leave it for now. With a beer with such a high starting gravity I'd expect it to take a little longer to ferment out.

One question I do have is what quantity of yeast did you pitch? I would have used two packs of the WLP yeast for a beer with that starting gravity. If you used less then it may result in a slower than desired fermentation.

I just used one pack - I used the same yeast and quantity before for a Belgian quad and it reached 11% fairly briskly! But every brew is different and that previous one had Belgian candi and brewing sugar in fairly hefty quantities. I'm not in a hurry for it to finish, and as long as it's healthy I'm happy. Good to know for the future tho'.

Agentgonzo · Nov 8, 2024

Was the temperature the same on your previous brew? A difference of a few degrees can have a large impact on how quickly it ferments.

My last brew fermented at 19° and was noticeably slower than other brews at 21.

I would expect your temperature of 18.3 to slow the yeast down somewhat

DeniqueCoelum · Nov 8, 2024

Agentgonzo said:
Was the temperature the same on your previous brew? A difference of a few degrees can have a large impact on how quickly it ferments.

My last brew fermented at 19° and was noticeably slower than other brews at 21.

I would expect your temperature of 18.3 to slow the yeast down somewhat

I think it was a bit warmer, if I recall rightly! I might pop the temp up a couple of degrees, see what that does.

Nottsbeer · Nov 8, 2024

I'm brewing a Trappist style at the moment, using Flushed Nun (CML) yeast. Like you this is more of a steady slow burn. Has taken a week to get to FG (around 1.016). This is normal for this brew I've found. Will leave it another week to do it's job before bottling. Like you, other beers can be done in c.4 days! You can always up the temp a bit. Mine is at 22 and very happy

DeniqueCoelum · Nov 8, 2024

Nottsbeer said:
I'm brewing a Trappist style at the moment, using Flushed Nun (CML) yeast. Like you this is more of a steady slow burn. Has taken a week to get to FG (around 1.016). This is normal for this brew I've found. Will leave it another week to do it's job before bottling. Like you, other beers can be done in c.4 days! You can always up the temp a bit. Mine is at 22 and very happy

That sounds rather wonderful.

Keen to do a Trappist style myself at some point. I shall follow your lead on this one - cheers!

Nottsbeer · Nov 8, 2024

DeniqueCoelum said:
That sounds rather wonderful. Keen to do a Trappist style myself at some point. I shall follow your lead on this one - cheers!

I'm sure yours will get there and taste great

.

Agentgonzo · Nov 28, 2024

Nottsbeer said:
I'm brewing a Trappist style at the moment, using Flushed Nun (CML) yeast. Like you this is more of a steady slow burn. Has taken a week to get to FG (around 1.016)

That's why what I'm seeing too. First time brewing with flushed nun

Nottsbeer · Nov 28, 2024

Agentgonzo said:
That's why what I'm seeing too. First time brewing with flushed nun
View attachment 106249

I did a stepped mash on the Trappist style and I don't know if that resulted in more fermentables, or if this yeast is a beast, but my FG was 10pts lower than expected!! Will be interesting to see where yours finishes compared to your predicted FG.

Agentgonzo · Nov 28, 2024

Nottsbeer said:
I did a stepped mash on the Trappist style and I don't know if that resulted in more fermentables, or if this yeast is a beast, but my FG was 10pts lower than expected!! Will be interesting to see where yours finishes compared to your predicted FG.

I'll. try to remember to post the results. It actually started at 1.050, but I accidentally purged the start of fermentation from home assistant after I'd had a few to drink. I mashed at 65º for 60 minutes, then 72º for 10 minutes. Fermenting at 20ºC.

Agentgonzo · Dec 5, 2024

Agentgonzo said:
I'll. try to remember to post the results. It actually started at 1.050, but I accidentally purged the start of fermentation from home assistant after I'd had a few to drink. I mashed at 65º for 60 minutes, then 72º for 10 minutes. Fermenting at 20ºC.

Took 11 days to fully ferment out. I'm going to give it until the weekend to clear, then bottle.

Nottsbeer · Dec 5, 2024

Loo

Agentgonzo said:
Took 11 days to fully ferment out. I'm going to give it until the weekend to clear, then bottle.
View attachment 106489

Looks like it is around 1.007 - were you expecting it to go so low? Looks like my graph as well

Agentgonzo · Dec 5, 2024

Nottsbeer said:
Loo

Looks like it is around 1.007 - were you expecting it to go so low? Looks like my graph as well

No, I wasn't. But the ispindel is nutritiously unreliable (can be as much as 5 points out, but normally it over reads rather than under reading).

I'll bottle it this weekend and measure it properly and let you know

MashBag · Dec 5, 2024

Larse said:
Too much sugar isn't a thing, otherwise wine making wouldn't happen. To be fair though, some yeasts don't have very high alcohol tolerance (hence wine yeast), but that wouldn't be the case here.

So too much sugar is a thing then

you can't have it both ways

MashBag · Dec 5, 2024

Agentgonzo said:
No, I wasn't. But the ispindel is nutritiously unreliable (can be as much as 5 points out, but normally it over reads rather than under reading).

I'll bottle it this weekend and measure it properly and let you know

Resident luddite here: Does make me wonder why anyone bothers

MashBag · Dec 5, 2024

@peebee is typing

Agentgonzo · Dec 5, 2024

MashBag said:
Resident luddite here: Does make me wonder why anyone bothers

You're right. It's not perfect. I bet you're using your phone or computer to access the forums. You should return to your abacus.

Slow fermentation... or is it?

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