Stuck Tripel with WLP550

[Gibbnal]

I've got an interesting stuck fermentation. I brewed a 1.080 Tripel 10 days ago. Everything went great and I pitched a decanted 3L stir plate starter of WLP550 at about 64F. I had about a gallon of extra wort/trub left over and pitched a tiny 6 month old stored bit of WLP550 in that. The gallon stayed in the house at about 70F and the full batch went into the temp controlled chest freezer.

My fermwrap malfunctioned on the big batch and dropped to 59F in the first 12 hours. I fixed the issue, swirled the fermenter and had the temp up to 64 in a couple hours. Active fermentation soon began the next day and I thought all was well. I went ahead and raised the temp one degree a day up to 70F as planned.

After 10 days, the way under pitched gallon is sitting at 1.012 (tasting great) and the big batch is hung up at 1.036 and waaay sweet.

So what to do? I swirled it up really well and raised the temp to 74F, but am doubtful. And how does a few ml of old yeast ferment out the same wort completely? Will a packet of rehydrated US-05 or Nottingham do anything?

 

[GuldTuborg]

The temperature control would seem to be the problem, at first blush. Ron Jeffries at Jolly Pumpkin has said that 550, if shocked by a steep drop in temperature, tends to go to sleep permanently. If you've maintained sanitation well in the gallon batch, you could always use that as a second "starter" and pitch some of it. I might try that first if it's an option. Otherwise, I'd just rehydrate a packet of T-58 or something similar. Maybe there are other tricks, but I don't think I've ever used that yeast.

 

[Gibbnal]

Yeah, I could just swirl it up the gallon and dump 2qts into the fermenter. Or would it be worth washing and adding to a bit of starter wort for a few hours first?

 

[daksin]

I've had good luck boiling a couple ounces of sugar and a bunch of yeast (bakers yeast, in my case) in a little water and adding that. The simple sugar wakes up the yeast and gets them working again, and the boiled dry yeast provides nutrients. Something to try if it's really really stuck in a week or two.

If the gallon is clean, I would make a starter from it, and re-pitch that at high krausen, though. Most people don't keep that satellite real clean, though, which is why I didn't recommend that first.

 

[ReverseApacheMaster]

Rack off the cake on the gallon batch and dump the cake into the big batch. That should get it going. Just keep it around 70F or higher.

 

[solbes]

Rack off the cake on the gallon batch and dump the cake into the big batch. That should get it going. Just keep it around 70F or higher.

+1, great idea.

 

[Gibbnal]

Thanks for the input, everyone. The yeast in that gallon batch seems to be my best bet. I'm going to give the agitaiton/warmer temps a few more days and take another gravity reading first, though.

Daksin - I had the same concern about potential contamination in that extra gallon, but it's really hard to resist. Getting it going on some fresh wort can only help.

As an aside, I am still blown away by how a tiny pitch of yeast went through a 1.080 wort like that. Makes me rethink my starter size for that style of beer.

 

[Gibbnal]

The gravity only changed from 1.036 to 1.035 so I took the lazy route - dumped the whole gallon batch into the BB and left the temp at 75F. It does appear to be going again.

 

[ChillWill]

Wow, I didn't think it'd be possible to stop WLP550 when it gets going, it's a beast and kicks out a lot of heat in my experience, although I've never let it drop to 59f.

 

[Gibbnal]

Looks like it ramped up and is coming back down. I'll get a gravity reading in a few more days. Curious to see what the 75f temp did to the last third of fermentation. Smells like squashed bananas in the fermentation chamber. I hear monkeys...

 

[Gibbnal]

Everything has stopped and the surface is clear. Gravity is now 1.015 - not quite the 1.012 of the small batch, but I will take it. 81% attunuation from a stuck batch is ok. Nothing odd about the taste. Mildly phenolic, some warmth and a touch of sweetness. Will bottle this in a week or so.

 

[GuldTuborg]

I'm glad everything worked out. Giving it a week at the same temp is a good idea; it might be slowly going still.

 

[Gibbnal]

So I finally bottled this. It dropped another point to 1.014 over the last two weeks. Seemed pretty normal after all the fuss - no particularly odd favors, although I can't help but think something be wrong with it.