First time using WLP002 - airlock activity stopped after 2 to 3 days?

I am using WLP002 for the first time in my oatmeal stout recipe. I made a 1 liter yeast starter and pitched the starter this past saturday (late afternoon) and first signed of air lock activity was Saturday night nothing crazy but a bubble about every two to 3 seconds maybe. This same activity continued through Sunday, but when I came home from work Monday I noticed there was no longer any activity in the air lock. I know airlock activity is not always an indicator of fermentation but I just replaced the rubber gromet on this plastic fermenter and the seal between the airlock and lid is solid, I have also never had issues in the past with "no airlock activity" in any of my brews. Is this normal behavior for this yeast?

 

The only brew I did with WLP-002 was pretty similar. I had decent activity then it quickly dropped to next to nothing by the third day. I had a point or two more drop on the hydrometer readings by the end of the week, but nothing after that. Even after some yeast rousing.

 

Sounds about right, rise temp to 21C/70F for 2/3 days in order for yeast to finish cleaning-up and you're pretty much done

 

Gravity is only at 1.027. Tasted the beer and it was definitely sweet and yeasty and maybe a hint of sourness....I think there might be an infection which would make it my first in my 8 years of homebrewing.

 

I doubt that you have an infection. Instead I think you are tasting the combination of yeast bite and acetaldehyde from incomplete fermentation. To get an infection in the primary that would sour your beer you would have to be incredibly sloppy with sanitation as the bacteria that sour beer require oxygen which should be lacking at this point in the primary fermenter. Let this beer sit for another 10 days and sample again. If it still tastes sour, let us know.

 

Thanks RM. I was shocked if it was infected as well as am super anal about sanitation .I am just worrier. I took the temp of it as well and Im at 65 degrees F. I have a heater fan up against the fermenter right now....going to heat it up a couple degrees and see how that helps.

 

WLP002/WY1968ESB is sensitive to temperature drops below 65*F, especially sudden ones. It can prematurely drop out and form a rubbery yeast cake that resists the most vigorous attempts to swirl it back into action.

To get this to fully finish, you'll want to warm it into the 68-70*F range then use a sanitized metal spoon or similar object to chop/stir that cake up off the bottom. Give it another week after that before checking the gravity.

Is there any lactose in your stout recipe? If so, that will throw off the expected FG some since it's not fermentable.

 

No there is no Lactose in this recipe. have you had successful fermentations when stirring up the yeast cake? I will heat it back up to achieve a slightly higher temp, but will that alone help the fermentation process without stirring as there is still yeast in suspension? I do plan to ferment this beer for 2 full weeks in the primary.

 

Yes, I've had stirring up the yeast cake (after a slight warm-up) help a stalled fermentation finish. I've had it not work as well as I would have liked too.

The problem you may experience with this batch is that WLP002/1968ESB drops out of suspension quite thoroughly upon a temp drop when activity is falling off. Simply warming it up may have little or no effect.

I'd certainly give it two weeks primary before checking the gravity again. Hopefully, you won't have to undertake any extra efforts.

 

Ya lesson learned with the yeast for sure. Next time I use it I will def be using a heat mat to hold the temperature to 68. Earlier this week I used a space heater and was able to heat the beer up to 70 degrees (checked by placing my thermometer through air lock hole). once I reached that temperature I picked up one end of the bucket and dropped it on the title floor gently enough to not create any sloshing in the beer (i think i sloshed once because i was seeing how hard I could drop it). I did notice after 20 minutes I was starting to see air lock activity - about a bubble every 3 to 5 minutes. But the day after I did not see anymore activity.

Anyway if after 1 more week the gravity does not drop is it worth it to pitch another yeast starter? If the gravity gets stuck at 1.027 I think this will be overly sweet for an oatmeal stout even though my SG was at 1.071.

 

Repitching on a beer that's gone from 1.071 to 1.027 isn't the answer IMO. You're tossing those new yeast cells into a rather unfriendly environment. The result is usually some excess yeast in the batch, but that's it. You've got a huge number of yeast cells already there if needed. If it stops at 1.027, gently stir that rubbery cake up off the bottom and give it another week.

Keep in mind too that an 1.071 OG oatmeal stout has plenty of unfermentables in it. With 002, you may end up finishing at around 1.020 on that beer under ideal conditions.

 

Yes, I fully agree with this.

002 is notorious for floccing out a bit early, but it's also well known (in my experience anyway) for a really fast fermentation. Check it again in a week... but I bet if you're able to keep it warm enough, you'll see a drop closer to 1.020 than 1.027.

 

Cool thanks for the input guys. I just really hoping it falls closer to 1.020. I Dont want an overly sweet oatmeal stout.