ANOTHER stuck fermentation post...

[Steviewell]

Im sorry for posting yet another post re stuck fermentation but this is the third batch in the last 4 Ive had problems with.

This time, Grand Cru. Made to 9 litres as per the instructions, it was a little but on the warm side but I left to cool to 25C before pitching the yeast. Also note I hydrated the yeast in 25C water as per packet instructions. (It is worth pointing out I have very accurate temperature measurement kit from work - I am an instrumentation engineer by trade :)

Initially fermentation was good, a mighty OG 1.072 on Sat 18/4 dropping to 1.022 by my next check Sat 25/4. Next check on Wed 29/4 and still 1.022.

In hindsight 25C is a little hot, maybe 21/22C better, but I dont think high enough to kill the yeast (???).

On the Wed I pitched more dry yeast (Young's Ale Yeast) without rehydrating first. temperature this time about 21C but has dropped lower to about 18C lowest since. Unfortunately today still at 1.022 so the yeast has had no effect.

Any thoughts? I have today upgraded my temperature control system so it should maintain a fairly steady temp - whatever I choose, which I have set for 21C. Should I syphon off the beer into a new bucket and pitch yet more yeast and give it another week? Should I add some sugar this time too?

Any input much appreciated I am at my witts end!

 

[mickthetrick]

allot of high gravity beers finish high.
what does the recommended finished gravity say it should be with the kit? 25degrees is a bit high but shouldn't effect the yeast at that temp

 

[MyQul]

25C isnt hot enough to kill the yeast. Have you given it a gentle stir to rouse the yeast back into suspension.

 

[Steviewell]

Hi Mick thanks for your help. It tells me to expect 1.010 or less for the FG.

 

[Steviewell]

25C isnt hot enough to kill the yeast. Have you given it a gentle stir to rouse the yeast back into suspension.

Ive not actually, is that all that is needed do you think? Its worth a try anyway and I will do now! :)

This is my third stuck ferm though, I was wondering if I am doing anything else wrong maybe. Is temperature the only factor for stuck ferm?

 

[MyQul]

If a yeast is highly flocculant it 'clumps' together then sinks down to the bottom of the FV quickly . Yeast can only do its work while in suspension. If it's chillaxing on the bottom of your FV it wont be fermenting your wort

 

[MyQul]

Im sorry for posting yet another post re stuck fermentation but this is the third batch in the last 4 Ive had problems with.

Do you aerate your wort?

 

[Steviewell]

Do you aerate your wort?

Im not even sure how to aerate my wort! :lol: Is this something I should be doing? can you explain further please?

 

[MyQul]

Not even mentioning aerating wort on kit instructions is one of my bug bears! Grrr :-x

Yeast need oxygen to reproduce (clone themselves) to then have enough cells to then ferment your wort. Its very simple to do. After you've mixed everything together and before you sprinkle your yeast on top. Get a sanitised whisk and give it a good whisking. If you don't have a whisk get a sanitised jug get some of the wort and pour it back into the main body of the wort from a height. Do this a few times. Your looking to get a nice frothy head on the top of the wort.

Also a note about sprinkling the dried yeast on top of the wort - It can kill up to half of the yeast. So if you didn't aerate plus simply sprinkling the yeast can lead to a stuck brew. You really want to rehydrate your yeast.

https://www.homebrewersassociation.org/how-to-brew/rehydrating-dry-yeast/

or google "rehydrating yeast homebrew" if those instructions aren't clear enough

 

[Steviewell]

You are a great help MyQul thanks, but a few questions please:

1. I am about to stir my wort following your previous post - do I want to scrape the bottom and disturb the trub or just a gentle "top stir".

2. I think I have aerated - going by your explaination I didnt whisk the wort before pitching but I always give it an almighty stir and there is a big frothy head on it.

3. I usually dry pitch the yeast onto the big frothy head, should I be clearing a way to pitch directly onto the liquid? On this Grand Cru (and future now anyways I think) I will always try to rehydrate now, but going by your link....

4. They say to rehydrate the yeast onto about 40C water (!) That seems very high, is this a typo? I rehydrated with 25C water for this batch.

Thanks again for your help!:

 

[MyQul]

1. You want to get the trub (along with any flocced out yeast) back into suspension so scrap the bottom. Do it gently though as you don't want to introduce oxygen to your beer at this stage.
2.Sound like you aerate your wort to me. The intention is to get as much oxygen in there as you can whatever way you do it.
3. Not really, the froth subsided fairly quickly usually and the yeast then makes its way into the wort.
4. The link says 35C-41C. Whenever I rehydrate yeast (I don't do it very often as I usually repitch some of the trub from a previous brew into the next one) I usually err on the side of caution and rehydrate at 35C although as I understand it yeast is OK up to 45C

 

[Steviewell]

Top man MyQul thanks a lot! Im off to stir my wort now! Cheers!:thumb:

 

[MyQul]

Hopefully it'll get going again.

As a side note that's a pretty big beer your brewing - there may not have been enough yeast in the kit, so thats why it's stuck.