Author Topic: Time to reach FG/full attenuation?  (Read 460 times)

Online Bel Air Brewing

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Time to reach FG/full attenuation?
« on: February 24, 2020, 04:03:54 PM »
On average, what is your experience with lagers fermenting at 50 - 54 degrees to reach full attenuation and FG? One week, two weeks, more?

Our Czech Pils is chugging/bubbling away happily at 52F. It's been 8 days now, and the CO2 bubbles in the blow off show no sign of abatement. A series of 3 bubbles are expelled at 5-6 second intervals. Non-stop.
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Offline denny

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Re: Time to reach FG/full attenuation?
« Reply #1 on: February 24, 2020, 05:02:40 PM »
I firmly believe that bubbles alone don't tell you when a fermentation is finished.
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Online Bel Air Brewing

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Re: Time to reach FG/full attenuation?
« Reply #2 on: February 24, 2020, 05:04:52 PM »
I firmly believe that bubbles alone don't tell you when a fermentation is finished.

I understand. But what is the average length of time for most lagers at these temps? Is two weeks normal? 3 weeks?

When the CO2 bubbles stop completely, is the ferment complete?
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Offline ynotbrusum

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Re: Time to reach FG/full attenuation?
« Reply #3 on: February 24, 2020, 05:14:36 PM »
I agree with Denny as to finish of fermentation - don't rely on the bubbles; but, you can pretty well rely on the bubbles as evidence that fermentation is continuing.  However, off-gassing due to temperature change or disturbing the fermenter post-ferment can occur, which isn't the same as a steady bubbling of active fermentation.

All of that said, my lagers finish typically in a week to 10 days (with a very healthy pitch of yeast, of course), but occasionally I have an outlier that takes a couple weeks.  I use a Tilt hydrometer, so I can always monitor changing gravity and stabilized gravity.  I don't typically spund, but with the Tilt, it makes it easier to follow when you are approaching the expected final gravity.
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Offline denny

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Re: Time to reach FG/full attenuation?
« Reply #4 on: February 24, 2020, 05:23:54 PM »
I firmly believe that bubbles alone don't tell you when a fermentation is finished.

I understand. But what is the average length of time for most lagers at these temps? Is two weeks normal? 3 weeks?

When the CO2 bubbles stop completely, is the ferment complete?

For me it can be 5-14 days.  No, when bubbles stop it simply means that CO2 is no longer coming out of solution. 
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Offline Visor

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Re: Time to reach FG/full attenuation?
« Reply #5 on: February 24, 2020, 05:35:16 PM »
 Agreed that bubbles alone don't guarantee that your at F.G., but 3 every 5 seconds is way more than simple off-gassing. Depending on the F.V. when bubbles slow down to more than ~30 second intervals I figure it's time to start checking gravity - for ales as well as lagers.
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Offline hopfenundmalz

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Re: Time to reach FG/full attenuation?
« Reply #6 on: February 24, 2020, 05:49:02 PM »
Commercial lager breweries are around 5-6 days.
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Offline majorvices

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Re: Time to reach FG/full attenuation?
« Reply #7 on: February 24, 2020, 05:49:45 PM »
It is going to depend on a lot of things, including how healthy your yeast was and how much you pitched. also what temp you are fermenting at and what temp you ramp up to. I like to start my lagers around 50degrees and ramp up to high 50s after 72 hours. Fermentation usually takes 5-10 days.

Offline Robert

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Re: Time to reach FG/full attenuation?
« Reply #8 on: February 24, 2020, 06:50:27 PM »
My lagers, around 50°F, are within 0.5-1°P of FG and spunded 4 days from pitching, and finished, carbonated, diacetyl reduced, and ready to cold crash and lager by 6-7 days.
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Online Bel Air Brewing

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Re: Time to reach FG/full attenuation?
« Reply #9 on: February 24, 2020, 07:21:05 PM »
My lagers, around 50°F, are within 0.5-1°P of FG and spunded 4 days from pitching, and finished, carbonated, diacetyl reduced, and ready to cold crash and lager by 6-7 days.

It is going to depend on a lot of things, including how healthy your yeast was and how much you pitched. also what temp you are fermenting at and what temp you ramp up to. I like to start my lagers around 50degrees and ramp up to high 50s after 72 hours. Fermentation usually takes 5-10 days.

The yeast was over pitched. A healthy 3rd gen starter, plus a smack pack (active, but not real active). We hit the wort with 40 seconds of pure O2 after racking to the conical. Lag time was 8 hours, with healthy fermentation / CO2 discharge every 4 seconds. Temp was held steady at 49 F. Now the CO2 is blowing every 8 seconds, like clockwork. With a rapid triple-bubble (boom-boom-boom) in the qt. jar.

I'm guessing another 5 to 7 days to finish. We did bump the temp up to 55.

We took a sample yesterday for a taste after a full 8 days in the fermenter. Still very sweet, but the hop bitterness has smoothed out considerably.

Wyeast 2278, Czech Pils.
« Last Edit: February 24, 2020, 07:42:15 PM by Myron Oleson »
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Online BrewBama

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Re: Time to reach FG/full attenuation?
« Reply #10 on: February 24, 2020, 08:29:28 PM »
FWIW: The Tilt hydrometer has really opened my eyes to what is happening both before and after an airlock is active. I’ve seen gravity drop further even after the airlock is no longer active. I’ve also see gravity drop before the airlock becomes active.

I used to plod along 10-14 days but began pitching more yeast which made all the difference. My lagers have now been taking ~6 days to finish fermentation.  The difference is amazing.


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Offline Robert

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Re: Time to reach FG/full attenuation?
« Reply #11 on: February 24, 2020, 08:29:54 PM »
My lagers, around 50°F, are within 0.5-1°P of FG and spunded 4 days from pitching, and finished, carbonated, diacetyl reduced, and ready to cold crash and lager by 6-7 days.

It is going to depend on a lot of things, including how healthy your yeast was and how much you pitched. also what temp you are fermenting at and what temp you ramp up to. I like to start my lagers around 50degrees and ramp up to high 50s after 72 hours. Fermentation usually takes 5-10 days.

The yeast was over pitched. A healthy 3rd gen starter, plus a smack pack (active, but not real active). We hit the wort with 40 seconds of pure O2 after racking to the conical. Lag time was 8 hours, with healthy fermentation / CO2 discharge every 4 seconds. Temp was held steady at 49 F. Now the CO2 is blowing every 8 seconds, like clockwork. With a rapid triple-bubble (boom-boom-boom) in the qt. jar.

I'm guessing another 5 to 7 days to finish. We did bump the temp up to 55.

We took a sample yesterday for a taste after a full 8 days in the fermenter. Still very sweet, but the hop bitterness has smoothed out considerably.

Wyeast 2278, Czech Pils.

Yes, it will depend on the yeast.  My results as cited are with German lager yeasts, such as WY2206, WY2124, and WLP833.  The Czech yeast may behave differently. 

Another very significant factor not to overlook is zinc.  Most worts are deficient in this one nutrient, which can make a difference between one week and two week fermentations. I dose zinc sulfate in the fermentor, but nutrients like Servomyces or Wyeast nutrient can be used to supplement zinc as well.
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Online BrewBama

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Re: Time to reach FG/full attenuation?
« Reply #12 on: February 24, 2020, 09:10:43 PM »
... Wyeast nutrient can be used to supplement zinc as well.

+1. I had a Danstar Regional Rep recommend Wyeast nutrient as a go-to — even over their own brand of nutrient. That’s a pretty strong endorsement IMO.



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Online Bel Air Brewing

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Re: Time to reach FG/full attenuation?
« Reply #13 on: February 24, 2020, 09:34:14 PM »
... Wyeast nutrient can be used to supplement zinc as well.

+1. I had a Danstar Regional Rep recommend Wyeast nutrient as a go-to — even over their own brand of nutrient. That’s a pretty strong endorsement IMO.



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... Wyeast nutrient can be used to supplement zinc as well.

+1. I had a Danstar Regional Rep recommend Wyeast nutrient as a go-to — even over their own brand of nutrient. That’s a pretty strong endorsement IMO.
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Never in over 20 years of brewing have we used any added nutrients. Is this something we need to do?
Note the date on the smack-packs was last November. 3 months old. First time using the Czech Pils yeast.

The CO2 explosions are now every 6 seconds as the beer has warmed to 53.9 F.
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Offline Bilsch

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Re: Time to reach FG/full attenuation?
« Reply #14 on: February 24, 2020, 09:40:49 PM »
For cold fermented lagers, in a standard cylindroconical fermenter.. 5-6 days to spund then 2 more to be fully carbonated. Open ferment, 3 days to spund then 2 more to carbonate. If you think you have healthy yeast and are pitching properly but are not coming close to these times then you don’t and aren’t.