[klosterfocke]

I'm an experienced lager brewer using 820 Octoberfest yeast for the first time and have encountered an unusual situation. I am 23 days into fermentation of a Marzen with an OG of 1.055 that is still vigorously fermenting, but has only gone down to 1.026. I used an active 2L 2 vial starter of fresh yeast for 5.5 gals and hit high krausen after 20 hours, but I'm still chugging along at about one bubble every 7 seconds in my airlock and a nice thick krausen head on the beer. I've never seen a beer ferment this slowly with this level of activity. Any thoughts on why it's so slow or mistakes I may have made. I know that this is a notoriously slow starter, but that wasn't the case with me. Any thoughts/similar experiences. Beer tastes OK, or at least as OK as a fermenting lager can taste.

[a10t2]

What's the temperature? I've used that yeast several times, always right around 50°F, and while it's slow it isn't THAT slow.

[klosterfocke]

I started at 50 and allowed it to rise to 55 over the first 3 days where it's stayed. I upped the temp 10 degrees this AM to 65 to coax it along. It's close enough to terminal to call it a diacytal/finishing rest.

[tom]

I had trouble with it the 2 times I tried it. I bet your diacetyl rest will help.
How big of a starter did you use?

[bluesman]

That is unusually slow. Have you checked the calibration of your fermentation chamber?

[klosterfocke]

2L starter at high krausen (2 vials) and reasonably short lag (20 hours). My freezer temps are right. In fact, I did a helles 6 days later that has already fermed out and dropped krausen using 838, and it was only 5 points lower,  right beside this beer in the same freezer. Damned lazy yeast.

[tntjr]

Just finishing up fermenting my 1.056 maerzen with WLP820 after 30 days.

1 tube starter built up to 4 liters was pitched at 45 and let it rise to 50 and held it there.

Activity peaked around day 4 but I continued to get bubles every 10 seconds for three more weeks. Things finally slowed down around day 29 and a two day rest at 60 seems to have finally finished it up.

Looking forward to sampling tomorrow when I keg it for lagering.

Tom

[klosterfocke]

Here's the thread closer for posterity. The beer finished out 6 days later at 1.014, lagered at 33 for a week, and took first in a MCAB qualifier 2 weeks later. I repitched this yeast, and got the exact same behavior; painfully slow but steady fermentation. Hope this helps someone in the future.

[redbeerman]

Haven't had this issue with 820.  I ferment between 48-53F in a swamp cooler and do a diacetyl rest at 60ish when the krausen has mostly fallen.  Beers turn out pretty darn good.

[Kaiser]

One of the stats I like to keep track of during my lager fermentations is the average gravity/day drop during the first 7 days after pitching. This gives me an idea how well the yeast is doing. For most lagers I can get 1 Plato/day.

Another interesting yeast characteristic you may want to look at is: “how close does your yeast get to the terminal gravity?” Terminal gravity is the gravity of a fast ferment test and may or may not be the final gravity you want to get. It does however tell you where the yeast has to stop b/c after that no more fermentable sugars are left. I, for example, experienced that WY2206 and WLP833 are having a rough time getting those last sugars even if they have been performing well during the first week of primary fermentation. For some beers, like bocks for example, this is desired as you want some residual fermentable sugars. But if they stall too early the beers will be too sweet. WLP 830, on the other hand, seems to have a much easier time getting to the terminal gravity and is thus a much better choice if you want beers that finish dry (Pilsner for example).

Just some food for thought as you are pondering the yeast behavior during your lager fermentations

Kai