AG ferments sticking

[henderjo]

Hi all, long time brewer into my 5-6 AG with a recurring stuck ferment issue. Today is brew day. Without going into what I had for breakfast... The only significant change/cause I can see is that I'm dropping all the O2 in the boil. I use a chiller, but siphon into the fermenter - so not much chance for agitation and reintroduction of O2. Even if i did, at about 30deg C, im not sure the liquid can take in much O2. Has anyone experienced similar issues? Appreciate any and all feedback.
John.

 

[contrarian]

Where are they sticking and what yeast are you using? Most of my AG brews have finished around 1.012-1.016 and have tasted fine!

 

[henderjo]

Good point, meant to include that... Starting at 1.035-40 and sticking at 1.025, only getting around a 10 point drop with saf lager in temp control at 12deg C, resting at 15deg C when it sticks, which doesn't seem to help. Neither does a stir once stuck. I've checked the hydrometer and it seems accurate. Beer tastes ok, luckily I also do alcohol, so I can bump it up before kegging, which is what I did last time. Mates went through two kegs in a night, so I think it's all there, I just want more from my ferment. I want to try something different this brew to help identify the issue.

 

[contrarian]

Have never used lager yeast so can't be much help but giving it a good thrashing with a slotted spoon will help or there's plenty of threads about oxygenating wort if you want to go down that road.

Some advice I got from a mate that worked was dissolving about 100g of sugar on boiled water, letting it cool and then adding to the fermenter. For me it helped kick things off again.

Other factors such as grain bill, mash temp etc. could play a part but it would have to be odd to finish that high!

I'm sure someone with a shed load more experience will offer some better advice!

 

[MCHammo]

What sort of time frame are we talking about? I've only done one lager. That went off like mad, dropping from 1.050 to 1.025 odd in about 3 days. It took another couple of weeks to drop to 1.016. Maybe I was doing something wrong (first beer and all), but it got there in the end. How long have you left yours for?

 

[contrarian]

I've only done ales so far, normally with an OG of 1.045-1.055 and have used s-04, us-05, wyeast 1056 and Irish ale. I ferment at about 18 degrees for at least a week and often 2 or more depending on what kegs I have that need filling.

If mine have stick it has been around the 1.020 mark and a mixture of swirling the fermenter, stirring the fermenter or adding some sugar has got them down a few more points sometimes coupled with bringing the temp up to around 22C.

I no chill so splash about half a cube into the fermenter, put the lid back on and shake the crap out of it for a couple of minutes and poor the rest in which seems to work ok.

Of you're not making a lager maybe try fermenting a bit warmer and see how that goes.

 

[yum beer]

You need to aerate the wort after chilling into the fermenter. Don't siphon, place fermenter under the tap and let it flow freely, thrash with a spoon as you go or pick up and shake it a bit.
Sounds to me like a lack of oxygen at the start of ferment, if you don't have enough the yeast cannot multiply enough to do a complete job.

 

[Camo6]

What yeast are you using and how much are you pitching? I'd also check your thermometer to make sure your mash temps are accurate. And as mentioned above thrash the crap out of it with a spoon or paint stirrer. Yeast nutrient wouldn't go astray either.

 

[henderjo]

Thanks all. My lagers take 2-3 weeks and a day or two resting at the end. I then drop the temp to 2degC for up to two weeks on the trub (that should get a few more comments lol), which works great for me. Siphon to keg, force carb and serve. I work on 4 to 5 week turn around. I can always speed it up if I'm thirsty

So I'm going to try agitating in my fermenter prior to pitching, my standard dry pack saf lager yeast straight into wort. Appreciate the replies boys.

 

[Pokey]

How are your nutrient levels? Make sure the yeast has everything it needs.

Good aeration and enough yeast are important too, more yeast will be needed for a lager than an ale.

 

[tazman1967]

You mention " standard dry pack Saf lager yeast ", you need more yeast numbers for fermenting a lager. You need 2 packs of dry lager yeast for a lager brew, or a 3 litre starter of liquid yeast IMHO.

 

[mikeintmba]

I used to use a 19 litre pot for brewing and my strike temp was 70 degrees which worked fine. When I bought a 50 litre pot and did the same thing my first brew fermented to 1025 and stuck. Turns out the mash temp was too high and all the sugars weren't converted. The grain into 15lts of 70 degree water cooled to 65 degrees quickly but the same amount of grain into 30lts of water stayed at 70 degrees.

 

[Bribie G]

Henderjo, how accurate is your mash thermometer? If it's reading a few degrees low and you think you are mashing at 65 but in reality you are mashing at 70 then you will produce more dextrins and less fermentable sugars.
A FG of 22 is very typical of a 70 degree mash and many brewers looking for more body, as in an English mild, do this deliberately.

I'd get another stick thermometer (Target or Big W ten buck ones aren't actually all that bad) and check against your current one to see if that's the problem.

Edit: you say that only your AG brews are sticking.
Previously the fermentability of the wort was set by the factory that makes the extract / kit.
You are now making your own "extract" so it's up to you to set your own fermentability.... I'd bet that's what's happening.

Edit: like Mike said

 

[Adr_0]

You mention " standard dry pack Saf lager yeast ", you need more yeast numbers for fermenting a lager. You need 2 packs of dry lager yeast for a lager brew, or a 3 litre starter of liquid yeast IMHO.

Yeah I would say lack of yeastie cells probably has a big part.

If you underpitch a lot, you get epic amounts of yeast growth at the start of fermentation to try to get to the right number of cells. This stresses the yeasties and they produce esters and other off flavours, plus drop out quicker rather than hanging around to properly attenuate your beer.

There are a few yeast calculators out there to get you in the ballpark of what you should need for your beer, and if you're using dry yeast rehydrating as per the instructions to get a cream of yeast can (apparently) reduce the initial stresses on the yeasties.

 

[manticle]

Are you using a refractometer to measure fg?
Sorry if it's been mentioned - reading/typing on a phone

 

[henderjo]

Bribie, Mike and Maticle great to have some tips from you lads. I think you've nailed it. I've been holding off buying a floating glass thermometer, thought this would be best? Already have two stick with dial type. I also have a digital from the still which I could try.

So, I'll agitate and watch my temp much closer. I'm only doing 20lts so I'd think one pack of yeast sufficient for the time being. I'm leaning toward mash temp now for sure. Thanks Bribie G ill aim for 65 and see how I go.

 

[Screwtop]

% Attenuation = 100 x (starting gravity - current gravity) / (starting gravity - 1)

So for your starting gravity of 1.035 - 1.040 fermented down to 1.020

100 x (1.040 - 1.020) / (1.040 - 1) = 50% which is very low.

Variations in mash temp will affect fermentability................ a little

Are you using dextrinous (less fermentable) malts such as Cara/Crystal in your recipe?

Fermenting at low temps requires a higher pitching rate. 2 packs of Saflager if you are fermenting at 10[SIZE=11pt]°C [/SIZE]- 12[SIZE=11pt]°[/SIZE]C

Are you using a Refractometer to test gravity?

What temp control method are you using?

 

[country_brewer]

Agree with tazman, make a starter to give the yeast a chance to multiply and get going, really easy to do and will cost you nothing to try.

 

[Keppmiestet]

Making sure your water and ph is right as well as mash temp when doing all grain is very important for good results, ph will effect efficiency of how much is converted, your mash temp will determine body and how many fermentables there are for the yeast to eat and your water minerals especially calcium levels will help with yeast health allowing them to keep chewing away at that wort lowering the FG .

 

[Ciderman]

Second AG brew and I'm a fair way off my FG.

1.074
1.071
1.063
1.049
1.045

Target gravity is 1.018

The last reading has been consistent since Thursday evening.

I'm not so sure temperature is my problem. I have a thermostat on a fridge and it was set at 18 degrees. It wasn't keeping exact temperature because I didn't realise I had to use a heat source as well. (Another amateur error)

It got as low as about 15 degrees but since I attached the heat belt to the thermostat it has kept correct temperature. I gave the yeast a mix up on Saturday and brought up the temperature to 21 degrees and no movement.

Can I save this? Do I need to pitch more yeast, and what is causing this?