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Low attenuation with WLP002

I brewed an oatmeal stout a few days ago using WLP002. It started fast and seemed to finish in just 4-5 days. But with an OG of 1.060, it was only down to 1.022, and I was expecting 1.015-1.018. It actually tastes pretty good out of the fermenter. I swirled it vigorously a few times to try to stir up the very firm yeast cake on the bottom. I also raised the temp from 68F to 70F, but the reading doesn’t budge. The stats say the attenuation is 63-70%, and I did get the low end of this. Should I just be satisfied with the FG of 1.022, or should I add another yeast to dry it out a little?

That vigorous swirling was a horrible idea and likely will lead to oxidation of your beer.

Was it an extract batch? If so it’s probably done. Extract tends to have a few less fermentable sugars and english ale yeasts are low attenuators.

It was all grain. I thought about the oxidation possibility, but figured there is mostly CO2 in the airspace as well as in the beer itself. At least I didn’t detect oxidation tasting it out of the fermenter just now.

What temperature did you mash at?


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This is from another forum from 9 years ago discussing this very topic: “I have done bitters with WLP002 where one time I let the yeast finish without bothering it, another batch, same grist bill and mash, where I roused the yeast and the beer finished much drier, by about 6 points. WLP002 is a fst fermenter and it flocs out like putty when left on its own. It’s the only yeast that I’ve used that has shown this type of behavior in lower gravity beers.”

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Leave alone for a week, if you don’t need your fermenter, and check it… I believe it’s done… You’ll just want to verify your findings.

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You’ll get less attenuation with a higher mash temp like that. 148-150 would probably have given you a few more points of attenuation but in an oatmeal stout you probably want more mouthfeel anyway.

Your grist bill would offer a few more clues to your attenuation. If you used a lot of c malts or less fermentable malts that would also keep it from going lower.

If you’re bottling I’d do as @sneezles61 suggests and take a couple gravity readings to be safe. If you’re kegging I’d get it packaged and on gas ASAP to try and offset the effects of oxidation.


If you haven’t opened the fermenter when you swirled it should be fine even if you opened it it’s probably fine just don’t want to splash it around. Generally what I do with my buckets is after a couple of weeks and fermenation has slowed I lift it by the handle and gently swirl the bucket haven’t gotten oxidation from it. You have more chance of oxidation on transfer.

Transfer to a secondary it’s not too late and this may rouse the yeast. Do it without splashing to try and avoid oxidation.

Never understood the logic of taking it off the yeast to “rouse the yeast”. Sounds like an exercise in futility to me.

Sometimes the yeast floccs early and poor attenuates. By getting the yeast in back in suspension it wakes up if you will. That is the logic. The more surface area of yeast the better its chance of doing its job in this case. So you aren’t transfering for clarity. I’m not sure yeast cares about logic though

sounds like urban myth to me. Yeast will consume all the available sugars and continue to replicate until they’re done. The only thing that’s going to “wake them up” is the introduction of more sugar.

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Getting yeast back into suspension can kick start the fermentation and get the FG a little lower. This is from the White Labs Website:

“High flocculators can require special attention to produce a well balanced beer. The yeast will often need to be “roused” back into the beer by gently swirling the carboy, or with a commercial fermentor, gently blowing CO2 into the bottom of the fermentor.”. A gentle swirl of the carboy releases a lot of CO2 out of the liquid so there is little risk of taking on O2.

Beechwood aging exists for the same reason as well.

I’ve done the same"aging" on birch wood… I really don’t see the paradigm…

Its about the flocc as well
Anheuser-Busch’s famous beechwood aging is designed to increase the contact area between the yeast and the beer. They start with long chunks of beechwood, which they treat with baking soda to reduce the already mild flavor contribution of the wood. A-B stacks these pieces in the Budweiser lagering tanks, and then they kräusen the beer by adding fresh wort. The wood forms a substrate to collect yeast, increasing the yeast/beer interface, as compared to a thicker layer of yeast at the bottom of the tank. It’s worth pointing out that they could probably get a similar effect using any non-reactive substrate, such as ceramic, although that wouldn’t make for good advertising.

Now I’ve got to buy some Bud to see what their pH is… Perhaps compared to other brews… It’s some what higher… Sneezles61

Nope. To each their own MO but once fermentation is started you’ll never see me swirling or stirring my beer. Luckily I have never had a reason for such nonsense. :stuck_out_tongue_winking_eye:

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I have to admit the few yeasts that I struggled with in this way I’ve never used again. Rousing shouldn’t be needed. I do like to experiment with as many yeasts as possible so I guess I might encounter it someday

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