Have a cream ale (OG ~1.059) that has been fermenting at the low end of US-05's range (57-59 degrees) for just about two weeks. Didn't test gravity, but still saw a decent krausen ring and airlock activity. Recently got a chest freezer, temp controller, and brewpad (for heating), and moved it into that at 72 degrees.

Fermentation did seem to be slowing (first couple days had a minor blow-off), but I wasn't sure if I moved it there too late.

Also have a saison that has shown airlock activity for 4 WEEKS (WL 565/saison II), and was thinking of moving that into the chamber as well to finish that mother out.

Is a week diacetyl rest too long (I believe there is another thread indicating 'no'), and can I simply move my saison into the chest as well to finish it out?

EDIT: My motivation for raising the fermentation temp was more to allow the yeast to finish fermentation (they seemed a bit sluggish at 57 degrees fermenter temp in my basement).

2 Answers 2


You can raise the temp to 64F and leave it there if you're concerned fermentation is going too slowly, but not much higher than that. That will give the yeast a gentle nudge, without sending them into overdrive.

As to the rest, a couple of days is more than enough and can help the yeast generally kick up a gear to clean up anything else they haven't yet taken care of (acetalaldehyde for example). But I wouldn't take it up to the mid 70s until fermentation has completely finished, or you may introduce esters and fruitiness, not really wanted in a cream ale, which you've accordingly tried hard to eliminate with the low temp ferment.

  • Regarding fruitiness, I see a lot of people reporting that US-05 fermented less than 60-62F gives off a 'peach' flavor in the final beer. Odd that you get more fruit with lower temps but I've seen enough people mention it to make me wary.
    – GHP
    Mar 28, 2012 at 17:15
  • Interesting, I don't get any peach at this point, but definitely a decent bit of diacetyl (by the time I raised the temp, the krausen had subsided)
    – Pietro
    Mar 28, 2012 at 20:16

IMO, a week isn't too long. But I question whether you actually need a d rest. Can you taste diacetyl? If not, you don't need the rest.

  • I suppose its more of a move to hasten fermentation. US-05 typically works quicker than this brew. I just want to make sure the beer is dry on the palette and that fermentation finishes. Once the fermenter itself reached 70 I gently shook/rocked to rouse the yeast (krausen still hadn't subsided).
    – Pietro
    Feb 22, 2012 at 20:51
  • Well, that's different, then!
    – Denny Conn
    Feb 22, 2012 at 21:15
  • 1
    I disagree about not tasting diacetyl meaning a rest is not necessary. If you can't taste diacetyl it could be because the alpha-acetolactate, a diacetyl precursor that's flavorless and odourless, hasn't oxidized yet to produce diacetyl. If you rack off too early, there's no yeast to then clean up the diacetyl produced by the AAL. see byo.com/stories/article/indices/18-brewing-science/…
    – mdma
    Sep 20, 2012 at 10:15

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