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Old 08-05-2007, 09:05 PM   #1
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Default Super fast lager ferment?

I brewed an Oktoberfest on 7/30, OG = 1.061. Pitched about 300 ml of yeast slurry from a 1 L starter and let it go @ 50 F. Everything proceeded normal at first - activity within 12 hrs, kraeusen after about 50 hrs. But then the kraeusen just died (never grew more than 2"), the activity slowed and has now nearly stopped.

Unable to RDWHAHB, I drew out a sample to check the gravity - 1.024 @ 62 F, ok.. so something has been happening.

This seems like an awfully fast fermentation to me. I was under the impression that lagers would take 1-2 wks for primary. Anyone have any thoughts or can you just alleviate my fears? When should I raise the temp for a diacetyl rest and how long should I hold it for?

FYI using wyeast 2308 munich lager

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Old 08-06-2007, 03:54 AM   #2
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How big is the batch size?

Fermentaion produces heat, so if it a big batch, perhaps the heat from the fermentation accelerated the process? Was inside a fridge? What sort of fermenter is it in?

I do my 25L batches in the fridge inside a plastic fermenter. The fridge is held at 8-9 degrees C, or 46.5-48 F, during the primary, the actual beer sits at about 10 degrees C, 50 F.

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Old 08-06-2007, 01:18 PM   #3
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This is why I plan to sanitize my controller probe and leave it inside the fermenter from now on.

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Old 08-06-2007, 05:43 PM   #4
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I have those stick on thermometers to get a sense of how warm the wort is before pitching the yeast. They do an adequate job. I was wondering if you used those on the side of the carboy inside the fridge. Would they give an accurate reading or read what the glass temp is? I assume the latter since the thermometer is on the outside of the glass but then again the wort is against the glass too.

Anyone know?

- WW

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Old 08-07-2007, 03:33 AM   #5
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batch size is 5 gallons.
I highly doubt that temp is the issue. While this is the first run for my homemade lager fermentation chamber, I tested it for 3 days before using it and it held temps perfectly - variation of about +- 3 degrees from target temp depending on when in the evening I remembered to change the ice out.

I was pretty careful about allowing the wort to cool all the way to lager temps before pitching. In fact, I may have pitched a bit cold as I set the thermostat to 46 F and let the wort continue to cool in the ferm. chamber for a couple hours before pitching. My imersion chiller had brought it to 62 F before transferring it to the carboy. After pitching, I raised the air temp to 48 F and pretty much held it there throughtout.

Furthermore, while I don't have any of the stick on temp gauges (ruined them all in water baths), I monitored the air temp fairly carefully and everytime I changed out the ice jugs, the chamber definitely felt cold. There is just no way it was off by that much. Certainly no way it was above 60 F. Besides, the airlock activity was never vigorous enough to make me think that the temp was too high.

Even then, I also suspected that the temp could be the culprit when I saw the activity slow so soon. So, I sanitized my digi thermometer probe and took a reading - 51 F, right on with the air temp readings (yes, I have calibrated it).

Meh, I'm not really worried anymore. Just kind of surprising.
Lesson learned: not having any homebrew to drink makes a homebrewer nervious about his/her homebrew.

I've started raising the temp up to 60 F now for a 36 hr. diacetyl rest. Then I will rack the fest and brew my doppelbock, which will be dumped on top of this yeast cake. At least that's the plan. Anyone have any thoughts on pro's and con's of yeast washing? How beneficial/necessary is it to remove the extra trub from the first batch?

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