Stuck Oktoberfest Fermentation

[jar1087]

Hi All!

I'm looking for some help on my Oktoberfest, which seems to be stuck at a gravity of 1.028 (OG of 1.059). I used WLP830 German Lager Yeast in a half gallon starter, pitched at 72F and then put in the fridge and brought it down to 50F. Five days into the fermentation, I took a gravity reading of 1.029 and it's now been fermenting for over three weeks and has barely moved. I would like to get it down to at least 1.020, or a few points lower if possible. I am planning a diacetyl rest at ~60F; how much can I expect that to lower the gravity?

I'm considering repitching some active WLP830 but don't know if that will do much for me. Any suggestions?

 

[jar1087]

Also, should I repitch before or after any diacetyl rest? And I should probably mention that I already tried rousing the yeast and raising the temperature by a few degrees.

 

[jar1087]

Reading more from a number of threads, I think that I will rack the beer off of the yeast cake and then harvest some of the yeast to make up a "starter" to get the yeast active and fermenting again. Then I will add this back to the beer in the second fermenter. Sound reasonable? After I (hopefully) get a bit more attenuation, I will bring up the temp to 60F for the diacetyl rest before crashing and racking for lagering.

 

[ThickHead]

Reading more from a number of threads, I think that I will rack the beer off of the yeast cake and then harvest some of the yeast to make up a "starter" to get the yeast active and fermenting again. Then I will add this back to the beer in the second fermenter. Sound reasonable? After I (hopefully) get a bit more attenuation, I will bring up the temp to 60F for the diacetyl rest before crashing and racking for lagering.

I see noone has really chimed in much advice to you in this thread. I too have an Oktoberfest in my primary and tomorrow is the 3 week mark exactly. I used WLP820 (2000 ml starter) which is the White Labs Oktoberfest Lager Yeast and have experienced a slowing of fermentation activity. I am not overly concerned with leaving the beer in primary for a month if necesarry before racking for lagering. I have taken three gravity readings so far, 1.066 OG, 1.026 after 2 weeks, and 1.022 after 18 days. The krausen has long since fallen and there looks to be little or no activity but it is still slowly fermenting down.

I suppose I am posting this info to let you know that I am experiencing fairly slow fermentation and I understand that this is not uncommon for an Oktoberfest. Your idea of repitching as stated above is definately a good approach to get the yeasties started moving again but it may be a good idea to wait just a bit longer to see if keeping the beer on the yeast cake another week works itself out.

 

[jar1087]

ThickHead,

Thanks for the feedback and that looks like it'll be a bruiser of an Oktoberfest if it drops a few more points!

I guess that my concern is that I'm now just shy of a month and between days 5 and 27 I only dropped 1-2 points. I probably should have been monitoring more between days five and about 22, when I took the second gravity reading, so that I could have intervened earlier, but I'm pretty sure that fermentation has (essentially) stopped now; this has been confirmed by gravity readings over the last few days. Hopefully, getting the yeast to wake up in a starter will help.

On a related note, I was planning on washing and storing this yeast, but now I'm wondering if I should wash what I have in the primary or hope that I build up enough yeast after I repitch and then wash that. Do you see problems with either method?

 

[ThickHead]

ThickHead,

Thanks for the feedback and that looks like it'll be a bruiser of an Oktoberfest if it drops a few more points!

I guess that my concern is that I'm now just shy of a month and between days 5 and 27 I only dropped 1-2 points. I probably should have been monitoring more between days five and about 22, when I took the second gravity reading, so that I could have intervened earlier, but I'm pretty sure that fermentation has (essentially) stopped now; this has been confirmed by gravity readings over the last few days. Hopefully, getting the yeast to wake up in a starter will help.

On a related note, I was planning on washing and storing this yeast, but now I'm wondering if I should wash what I have in the primary or hope that I build up enough yeast after I repitch and then wash that. Do you see problems with either method?

I don't think there is anything wrong with the yeast in your primary. I would feel good about washing that if i were you. In fact, I just finished boiling all the equipment I will use to wash the yeast from my primary tomorrow.

I don't have the most experience in the world but i don't see anything wrong with either method that you have proposed. If it's been near a month and you have verified that your fermentation has stopped at 1.029 i would repitch. You definately want to get the final gravity down to around 1.020 at least. 1.029 is way too high IMHO.

 

[malkore]

I agree, for the style and the OG, you should be able to get under 1.020, probably 1.015 really.

is this extract? all grain? partial mash? if you did mash, what was the mash schedule? and, how reliable is your mash thermometer?

I've only done one lager without real temp control (used my uninsulated basement landing in february to hold 50 degrees)...but I'd say its ok to let it warm up just a little more than what you've already tried.

if anything, that'll get some diacetyl removed, and may finish off the fermentation...assuming your mash temp wasn't so high that 1.029 is actually 'done'.

 

[michael.berta]

Assuming your original starter was with one vile you way underpitched. Check out the pitching rate calculator

Mr Malty Pitching Rate Calculator

if you started with 2 viles you would still would have needed twice the starter volume. I've also heard of people having lager fermentation issues when pitching high and bringing it down. Personally I pitch lagers at 45 degrees then slowly over the course of a week I raise it up to about 50 degrees. Then I do a D rest for a few days at 65 degrees (room temp). When you pitch cool and slowly warm the fermenter up the yeast can attenuate better.

 

[malkore]

not to start a big debate on pitch rates, but I don't make starters and never buy more than one vial or smack pack, and I never have had an issue with stuck or stalled fermentation. they always end up right in the target FG range.

 

[brispriggs]

Just wondering how this came out. Currently have a lager with 820 in primary going on 10 days. Has only dropped from 1.054 to 1.032.