another stuck fermentation

[johnluc]

Hi all, halfway through and my brew has stuck @ 1020, this is the 3rd in a row that has stuck at this reading, have tried stirring,no change, the only difference between my last 3 brews and the 20+ previosly is that i'm doing 27ltrs instead of 23-25ltrs,using s04 or s05,
is one satchet enough ?, should i pitch another satchet although at the start they all go off like a train for the first 4 or 5 days any suggestions :wha:
johnluc

 

[PD]

Is this AG extract or kit ?
Did you make any alterations to the recipe or its sugar when you altered the brew size to 27 litres...
If you have pushed a standard 23 litre kit to 27 litres you are unlikely to get a stuck ferment from the sugars as it would be weaker...what's your fermenting temps been like during this hot spell ?

 

[johnluc]

thanks for your reply pd its an AG brew, upped all ingriedients from original recipe (youngs special from GW book)by respective amounts,
have struggled with temps (its reaching 46oc here in france)but managing to keep a fairly steady 19-21oc. i don't think thats the problem as my other stuck brews were when the temps were much lower,
johnluc.

 

[EskiBrew]

using s04 or s05,
is one satchet enough ?, should i pitch another satchet although at the start they all go off like a train for the first 4 or 5 days any suggestions

In my experience it is very unusual for S04 to stick :thumb: - S05 on the other hand :hmm:
How long has it been at 1020?

 

[johnluc]

In my experience it is very unusual for S04 to stick :thumb: - S05 on the other hand :hmm:
How long has it been at 1020?[/quote]

coming up to 3 days now,as i said have done 20+ ag brews using so4 or so5 and its only my last 3 have stuck.

 

[theboytony]

Last time I saw something like this it was down to mash temp and them reading the thermometer wrong c instead of f or the other way round can't remember now

 

[BigYin]

is one satchet enough ?

Yes it is - although if you want to get really pedantic about it, I'm told that technically it is underpitching, however almost everyone probably underpitches, and they get away with it just fine :thumb:

If the fermentation started off fine as you describe, then I doubt there's been a problem with the yeast.

It's either got too cold, run out of fermentables, or run out of oxygen.

Of course yeast will also stop if the alcohol content gets too high, but there's no way that's your problem :lol:

I've had a kit stop at 1020 - I ended up bottling it at that, and it was widely touted as one of the best brews I'd ever made!

For you next brew maybe you could look into whether you're getting enough aeration at the start of the ferment??

 

[EskiBrew]

or run out of oxygen.

I'm not convinced this is the problem.

Fermentation occurs initially in an aerobic way with yeast rapidly reproducing while consuming the oxygen in the brew (hence the need to get good aeration at the start - to get the yeast multiplying rapidly) - during this stage they produce alcohol but not as much as when they move into the next stage - once the oxygen is all consumed, they switch into anaerobic mode and produce more alcohol.

What I'm trying to say is that the yeast does not need oxygen to continue fermentation and in fact it works best without oxygen once it has extablished a big enough colony. :thumb:

 

[johnluc]

thanks for your replies guys, certainly not got too cold, mash temp ok (my digital thermometer only read in oC), give it a good stir earlier this morning and seems to have a bit of action,will have to wait and see, still can't understand why this has just started to happen after 20+ ag with no problems. :wha:
johnluc.

 

[wilsoa1111]

i would tend to side with the guys going for mash temps being too high yeilding more unfermentables if anything-the digital thermos are only so gd(cheap ones espec poor, if waterproof probs ok) and have been know to vary by 3 degrees either way also are reckoned to need recalibrated once a yr in icewater(if pos if not again can only be so accurate)- easy enough to mess with a mash. as for fermentation if goes for 4-5days gd wouldnt be the yeast i wouldnt have thought. it also depends on the recipe some things like baltic porters are meant to finish way high like 1.032 is done-also suspended particles mess with hydros as they dont just measure sugars just density-if lots of yeast and stuff floating about (cloudy due to really active ferment) would add a bit-beersmith tends to say stuff done in primary when reaches 1.018 will then drop to 1.010 when bottled and cleared

 

[johnluc]

thanks wil, definetly not my mash temps,my thermometer is an expensive one (used to be a cooker engineer had to be accurate for trading standards) and is regullary calibrated, the only thing i can think of that i'm doing different is my sparge water goes in at about 85oc to bring the grain bed to sparge at 75oc whereas i used to sparge at 66oc same as mash temp.
johnluc.

 

[Hollow Legs]

hi johnluc,

I've only done 3 AG brews to date but I also bring my temp to 85degC for sparging and have had no problems with stuck ferments so far :pray: , not an answer to why you are having stuck ferments but maybe a solution? you can buy a beer enzyme over here that is used for said occasions (it breaks down more fermentables) I use it to make my pilsners (kits) dryer as it breaks more down if you get my gist.

Good luck

Colin.