Repitching, do I reaerrate my beer?

[reim0027]

So, I have a fermentation that I think has stalled. I want to repitch some yeast. After I make a starter, do I reaerrate my beer? It has been in the primary for about 3 weeks.

For reference, I am making a RIS. OG 1.100. Gravity now is 1.038. Target gravity is 1.024. I did an all grain batch, 60 minute mash, batch sparge. Mash temperature was 152 for the entire mash. 90 minute boil. Yeast = Wyeast Irish Ale, 1 gallon starter.

It went into the primary, and fermentation really took off, exploded out my blowoff tube. My SG has been at 1.038 for over a week (adjusted for temperature). I want to at least try repitching some Nottingham yeast.

 

[MBasile]

First Imperial stout I did took a month to ferment out, second one took two weeks with a 5 gallon (session IPA) starter. Point being, is it at a stable 1.038?

If you're certain that there are more fermentable sugars (meaning you're sure that you were actually at 152 for your mash) then yeah, you can aerate when you add additional yeast because, in theory, the new yeast will absorb that oxygen. However, if you aren't able to get fermentation restarted you've just oxygenated your final beer.

 

[reim0027]

My thermometer was in the mash the entire time, and it was 152 to start and 149.5 to end. My current SG is at 1.038 and has been that way for 1 week.

So, I'm at 60% attenuation. Wyeast Irish ale should get 71-75%. I have to assume there are more fermentable sugars in there.

 

[MBasile]

What I was getting at was the accuracy of your thermometer rather than ability to read it. However, since you've been a member here for over 3 years, I'm assuming you know your equipment.

Personally, I'd try to restart the current yeast before repitching. I don't know what temp you've been fermenting at, but maybe they yeast just got too cool?

 

[Revvy]

No, once you have fermentation happening, i.e. BEER in the fermenter, oxygen no longer is helpful, it become the enemy. Unless you like liquid cardboard.

 

[Yooper]

Where does the target FG come from? You're already up over 8% ABV, and probably at many ale yeast strains' alcohol tolerance levels. I would be very surprised if you could get it to 1.024 without using a high gravity yeast or champagne yeast. I don't think there is any way you'd hit 1.024 with a regular ale yeast no matter what, though- that's 76% attenuation and over 10% ABV.

 

[1ratdog]

champagne yeast. i did it with my stout, i did not re-aerate. got it from a 1.024 to a 1.019.

 

[Sithdad]

Where does the target FG come from? You're already up over 8% ABV, and probably at many ale yeast strains' alcohol tolerance levels. I would be very surprised if you could get it to 1.024 without using a high gravity yeast or champagne yeast. I don't think there is any way you'd hit 1.024 with a regular ale yeast no matter what, though- that's 76% attenuation and over 10% ABV.

1084 is 12% abv tolerant, according to the Wyeast website.

OP: I'd give it some time. Perhaps agitate the carboy a little (i.e. a gentle swirl). Get some more yeast back into suspension and perhaps that can get you a few more points of attenuation. Don't shake it just set it on a smooth surface and move the fermentor in a circular motion. You'll get some airlock activity, but that's going to be CO2 off-gassing. If you don't get anything else in a week or so you can try the repitch. You'll want to give it a little bit of O2 since the first yeast probably used up most of the O2 and you won't get much response from the 2nd yeast by pitching it into an O2 starved environment. Not too much O2 or you'll make liquid cardboard, like Revvy said.

 

[MBasile]

Where does the target FG come from? You're already up over 8% ABV, and probably at many ale yeast strains' alcohol tolerance levels. I would be very surprised if you could get it to 1.024 without using a high gravity yeast or champagne yeast. I don't think there is any way you'd hit 1.024 with a regular ale yeast no matter what, though- that's 76% attenuation and over 10% ABV.

WLP001 rocketed from 1.117 to 1.030, without issue. I do stand corrected on the aeration though, I was under the impression the added yeast would absorb it.

 

[Bensiff]

You could aerate the starter to help the yeast out; however, I don't know the curve of oxygen absorption so if you were planning on pitching the starter wort at high krausen you might oxygenate the beer. If you plan on decanting the starter beer you'd be gtg.

 

[reim0027]

I have a pretty good thermometer from Cole-Palmer. Brand new. I have already swirled it too. I'll try to pitch some Nottingham, from a starter and see what happens. If it works, great. If not, it'll still taste good, albeit a little sweet for a RIS.

I wasn't sure about the aeration. I know the aeration is designed to keep the yeast in the reproductive mode, increasing their numbers, then they go anaerobic and start to ferment. I knew aerating it would lead to oxidation. What I didn't know was if that was an acceptable trade off.

Thanks guys.

 

[freshhoarse]

I am considering doing the same thing to my Lord Fatbottom and all the research I've done is inconclusive... I brewed it just to see how high I could get my ABV. Initially, I pitched a stepped-up starter of 2 packs of Wyeast Pacman and I'm considering adding some champagne yeast (to the secondary) to put it over the top... BUT I prob won't re-aerate. I'll be checking SG in a week, and I'll try to remember to PM you with my decision. The nice thing about a barleywine is- there's no rush! Keep us posted on the ferment...

 

[reim0027]

1 week after repitching (gallon starter, 2 packets of Nottingham yeast), my SG is down to 1.032. I'll check for the next few days to see if that remains constant.

Question: Beersmith and brewcalcs.com are giving me 2 different ABVs for this batch. Which do I trust? OG 1.100, FG 1.032. Beersmith 8.9%, brewcalcs 10%