Stuck Fermentation?

[Iain Wishart]

Hi, I brewed a Neipa with a OG of 1050. For the first time I used Safale S33 yeast. It started fermenting quickly and airlock activity was crazy for 24 hours then stopped completely. Reading seems stuck at 1020 after 10 days. Plan was to transfer to secondary to dry hop then bottle but feel reluctant to continue given the reading or could this just be the beer fully finished fermenting and it's just been quick.

Many thanks for any advice.

 

[terrym]

If it has stuck a few tips in here
Simple strategies for dealing with stuck fermentations

 

[Iain Wishart]

Thanks for the link

 

[MrRook]

S-33 is notorious for high final gravities.

 

[Sandimas]

It's worth reading up on various yeasts and looking at their attenuation figure. I didn't do that until quite late in my homebrew career, now I track it each brew and it's pretty much spot on. Higher attenuating yeasts give a much lower FG than the medium ones. I've never used a low-attenuating yeast but it looks like S-33 is one: from the data sheet "Its low attenuation...." https://fermentis.com/wp-content/uploads/2017/10/SafAle-S-33.pdf

 

[Iain Wishart]

It's worth reading up on various yeasts and looking at their attenuation figure. I didn't do that until quite late in my homebrew career, now I track it each brew and it's pretty much spot on. Higher attenuating yeasts give a much lower FG than the medium ones. I've never used a low-attenuating yeast but it looks like S-33 is one: from the data sheet "Its low attenuation...." https://fermentis.com/wp-content/uploads/2017/10/SafAle-S-33.pdf

Thanks Darrell, really good to know, have used Safale S04 a few times and it fermented well and finished lower but the S33 went off like a rocket and was concerned re the reading but helpful to know regarding yeast and effect on attenuation so will check this for future brews. Cheers.

 

[Sandimas]

There's a good picture of the yeast packet here and it says Final Gravity - high
https://www.northernbrewer.com/products/safale-s-33-dry-brewing-yeast
I was looking for an attenuation figure. Most yeast manufacturers quote it and it's remarkably accurate, I've tracked it on 100 or so beers and it's usually within a couple of percent. I've just found it on another website: S-33 attenuation 68-72%. Plugging your figures OG 1050 / FG 1020, you're getting 60% attenuation ((50-20) / 50 x100) which is a little low, I'd have expected an FG of 1016 or so. But you're not far off.

Some yeasts have a real slow ferment tail, the very end of fermentation can seem really long. I've had some MJ yeasts still going after 3 weeks. Suggest keeping it warm enough (18C), maybe even raising the temp a bit (it won't hurt it at this stage) then checking it again after another 4 or 5 days.

 

[Iain Wishart]

Thanks for that, really appreciated. I'm relatively new to home brewing and am learning all the time That's really good to know re attenuation. I shall let it sit on and up the temp slightly and see where it's at in a few days. Thanks again.

 

[MrRook]

Attenuation is also dependant on the wort composition. A large percentage of specialty grains and/or a high mash temperature can result in a higher F G.

 

[Drunkula]

I use s-33 a lot, and so do a lot of kit brewers as it's in pretty much all those anonymous silver packets you get in kits, John Bull, Geordie and that.

I use it in all grains and haven't found the attenuation to be that bad but now you've got me wondering if part of the reason they use it with kits is to leave something behind after all the sugar has been added.