Anyone got suggestions to stalled fermentation problems before i go insane

[lindormonster]

Hi guys

Wondering if anyone can help as this is driving me mad

I have had multiple brews stall out when fermenting recently, This never used to happen and it seems to be happening regulary but not on every brew which is making it more confusing

I am using different yeasts and it seems to be happening randomly - sometimes yeast is fine then next time it stalls

I am brewing all grain on a 100 litre kit (only 20 litre batches) and brew mostly high strength beers (imperial stouts mostly but a few IPAs - all over 10%

I use a converted fridge with two shelves - heated with a greehouse heater controlled from inkbird

starting gravitys are allways within 4 points + / - of there they are supposed to be max and for the most part spot on

beer tastes fine and can be bottle carbed with no bottle bombs or anything else (even after leaving for ages)

No sign of infection at all

I have not always had this issue and it has started over the past year

Things I have looked at / Process:

Strike water - set to 81 degrees at HLT gives me 71 degrees when transferred to mash tun and a mash temp of 66 degrees once mashed in - Mash for one hour

Iodene test - All fine

Boil time - 1 hour to 90 mins depends on recipie

Cooled with plate heat exchanger (circulated and cooled until around 25 to 30 degree depending on yeast ( note I used Kveik quite a lot) )

Transferred to plastic bucket which has been sanitized before use and left for at least 15 mins

Temp checked to ensure correct pitch rate and yeast pitched

Sample taken on transfer and cooled to 20 degrees then SG taken with hydrometer (I also use refractometer during mash run off / sparge and boil to check gravitys are correct)

Fermentation starts fine within 24 hours

Temp controlled carefully and checked daily

Then we have either normal ferment OR it stalls after a few days normally around 30 to 50 points off from where it should be


Notes:

Yeast - I use WHC kveik (ebbegarden mostly) but have used Hordinial (WHC again), EBC-1118 champage yeast AND US05 - All are in date . I mostly use the EBBE and have multiple versions that i have harvested from starters and some washed slurry - All have produced complete full batches and also have stalled. I have pitched direct slurry, new pouches AND starters made from harvested starters , Slurry AND new pouches - Again mixed results of stalled and not stalled from the same source so can not pin point it to a certain batch nor way or creating (Starter , direct pitch or slurry). Interestingly my dad has used the same slurry and not had any issues and also with the harvested yeast but not on strong beers

ABV tolerance - I always stick to under the recomended BUT have also brewed batches well over the recomended / Highest tolerance level using same yeasts in the past

Fermentation temp - have fully calibrated the system and check the actual temp of the beer is in line with what it should be

Mash temp - was thinking it was mashing too high BUT have been militant with keeping it at 66 degrees over the past 4 brews - Have two that have stalled and two that are fine (note one is still going and I have not checked gravity yet but its still in full fermentation so will be another week how ever from the fact of how long its been going I am counting that as OK - am going to drop down to 64 degrees on the next run to see if it makes a difference as might still be a touch too high?

Interestingly - The latest stalled one is using EB-1118 champange yeast (Brut IPA) and its stopped at 1.050 which is odd as it should go down to 1.000 ??? - Have added amylase to kick it off again as i want it fully fermented out and its restarted again - This was after 2 weeks of fermentation and no activiry for over a week - OG 1.113

2 batches that have stalled recently were exactly the same beer - 1st time i used amylase on it and it fermented right down to 1.000 and is 14.6 % (using kveik ebbe yeast) second time it finished at 1.048 (from 1.115) - beer has been bottled and tastes lovely - no bottle bombs (5 weeks down the line)

Brewed a 14% imperial stout the other week and it was BANG on at every point with no issue - Brewed another beer on the same day (the one mentioned above) and it stalled - both had the same starter in there just chucked half in each at the exact same time and temp - EVERY part of the process was the same when i brewed these on the same day and pitched yeast at the same time

Hydrometer - I have two and have checked both are calibrated and working using plain water at 20 degrees (refractometer is also working fine and calibrated although i only use that up to point of pitching yeast its more for pre boil etc)


Conclude:

Only thing i can put it too at the minute is the mash temp being to high and I should drop to 64 BUT as mentioned above two beers at same temp can give two different results

Anyone got any ideas as its driving me mad - the beer tastes fine BUT im not hitting the correct ABV which is annoying as hell when you are aiming for 12% and get 8%

 

[Monkhouse]

You didn’t mention anything regarding getting oxygen into your wort before pitching your yeast, are you thrashing is with a paddle attached to a drill or using bottled oxygen with air stone etc? With wort at this high a gravity I would be wanting to get as much oxygen in there as I possibly could initially.
Just a thought, I can’t see anything else it could be considering how diligent your process is.

 

[AJA]

Have you checked your mash thermometer is working correctly?
Thermometers have a habit of breaking.

 

[lindormonster]

You didn’t mention anything regarding getting oxygen into your wort before pitching your yeast, are you thrashing is with a paddle attached to a drill or using bottled oxygen with air stone etc? With wort at this high a gravity I would be wanting to get as much oxygen in there as I possibly could initially.
Just a thought, I can’t see anything else it could be considering how diligent your process is.

Im cooling via heat exchange plate with a chugger pump - I have the hose that feedsback into the kettle up high so it splashes back into the pan. I also gravity transfer into the fermenter and again set it so it splashes heavily. TBH I used to go at it for 10 mins with the electric whisk ages ago but it didnt seem to make any difference

how ever ill getthe whisk out again next brew day and try it as im actually doing a split batch so can whisk one and leave the other and ee if any difference

Have you checked your mash thermometer is working correctly?
Thermometers have a habit of breaking.

Mash tun has a fixed thermo well thermomter in the front but I use a digital handheld prob to test temps - Both match up nicely



As its a old thread I have done a bit more playing and update would be -

I have been playing around with mash temps a bit and have dropped down to 65c from 66c and this has made a slight difference so the issue seems to be pointing at high mash temp leaving more non fermentable sugars

My findings also have pretty much come up with the fact that these are seriously high strength beers and the FG is just higher in them - from looking at some of the info I can find out about OG and FG for some of the big stouts from big breweries I concluded that the FG is never going to be mega low in them and yeast attenuations is always going to be lower when you push it as much as I do

Have a imperial pastry stout on the go at the min that was OG of 1.142 and has been sitting quite happily at 1.060 for the past week - Tastes great and appears to have finished its job

Im just putting it down to the style and working around it as the beer is coming out fine so I am working it into my recipies and working with it

I have also rebrewed a couple of things to test the theory out and they are coming out consistantly so im just rollling with it as the finished product is coming out how I want it and I think I was overhtinking it a bit too much

Not had one issue with overcarbonation or bottle bombs either so ill just keep rolling