Author Topic: Stopping Fermentation once FG is reached  (Read 6881 times)

Offline Big B

  • Big Bears Brewing
  • BeerSmith Brewer
  • ***
  • Posts: 26
  • WHY I GOT TO CLOSE MY EYES IF YOU AINT GOTS TO?
Stopping Fermentation once FG is reached
« on: December 18, 2011, 01:44:54 PM »
So I am fermenting my Double IPA.  My beersmith est FG is 1.018,  but I am at 1.015 right now.  I racked into the secondary and I am now dry hopping the brew.  Here is the question: 

I am still getting bubbles in the airlock.  Should I store the beer at a cooler temp in order to slow down the fermentation?  If I continue to let the beer sit at 68 degrees will it just keep fermenting until there is no sugar left at all?  Is cooling the storage in the secondary the best way to stop fermentation without killing the yeast, as I want to bottle condition.   I am using WLP California Ale Yeast.
Up Next: APA
Primary:
Secondary:
Just Bottled: Wuggies Winter Ale, Big Bears Belgian Dubble

Offline tom_hampton

  • BeerSmith Grandmaster Brewer
  • *****
  • Posts: 929
  • BeerSmith 2 Rocks!
    • Tom's Miata Racing Blog
Re: Stopping Fermentation once FG is reached
« Reply #1 on: December 20, 2011, 09:21:36 AM »
The short answer is: "you can't."  There are three ways to stop yeast action: 1.  chemical.  2. temperature 3.  filtering.   All of them are permanent and irreversible. 

The longer answer is that you don't want to (even though you think you do).  Especially, if you plan to bottle condition.  Bottling while there is an unknown quantity of fermentables remaining is recipe for overcarbonation (at best) and bottle bombs (at worst).  If it dries out completely below what you want, there are two possibilities: 1.  you mash-temp was too low (raise it by 4F next time), 2.  You have an infection of wild-yeast or bacteria. 

What was your OG?  CalAle is medium attenuating yeast at 77% or so.  That will vary depending on wort fermentability, though.  An all-pale-malt beer mashed in the 147F range might be a few points better than that.  If it was above 1.080 then you MIGHT have an infection.  FG is one of the hardest things to predict based on "formulas".  BS does a good job giving you an idea of what to expect...but, its only that.

Even if it IS an infection, its not the end of the world.  Its not likely to be harmful....watch and see what happens.  Give it time, let the FG settle out, and decide from there based on visual cues, aroma and taste. 
R.I.P.:Belgian Blonde
On Tap: Apfelwein, Kolsch(v2), Pumpkin Ale, Belgian Specialty 
Aging/Storing: Coffee Porter, Chocolate Porter, Flanders Red, English Barlywine
Fermenting: Maggie's Altbier
Next Up: PtE(1.1), Belgian Dubbel?

Working thru all BCS recipes

Offline pcollins

  • BeerSmith Master Brewer
  • ****
  • Posts: 69
  • BeerSmith 2 Rocks!
Re: Stopping Fermentation once FG is reached
« Reply #2 on: December 20, 2011, 10:45:17 AM »
+1 to the above.

You're not going to completely ferment out the beer to 1.000 SG or below. It will stop before that. You may be below the estimated FG but there is not necessarily anything wrong with that. Yeast will behave differently in different worts, different temperatures, different pitching conditions etc., so what BS says as an estimated FG may not necessarily be so in your set up.

There are a ton of arguments about transferring to secondary or not but I'm not going to go down that road. My only suggestion would be to wait until fermentation is complete before racking to secondary. If you have the same gravity reading for three days in a row you are very likely finished fermentation and you can transfer or leave it.

Also, sometimes in the transfer to secondary there is some agitation causing CO2 that may be in solution to come out of solution and cause some bubbling. I see that often in my process. I check gravity readings and determine that fermentation is complete and then transfer and the beer bubbles for a day or so after especially if I have dry hopped. The hops tend to act like nucleation sites for the CO2 and pull extra gas out of solution. Sounds like you have the same thing.

Offline Big B

  • Big Bears Brewing
  • BeerSmith Brewer
  • ***
  • Posts: 26
  • WHY I GOT TO CLOSE MY EYES IF YOU AINT GOTS TO?
Re: Stopping Fermentation once FG is reached
« Reply #3 on: December 20, 2011, 01:14:42 PM »
Thanks for the help.

OG was 1.073

I am not worried about it, just didn't know if there was something I didn't know about stopping when FG is where I wanted it.  I am going to let it ride and see what happens.

Thanks
B
Up Next: APA
Primary:
Secondary:
Just Bottled: Wuggies Winter Ale, Big Bears Belgian Dubble

 

modification