Move to Secondary = Rejuvenate Yeast??

[ADancy]

I always move my 5G batches from a primary fermenter to a secondary after about a week. Generally, by one week after brew day, there is no more indication of activity based on the airlock. However, in almost every case, after siphoning the beer over to the secondary, within a couple hours, the airlock starts to show signs of activity again. In some cases this will continue for another week or two or more.

What is going on in there that gets things going again?

 

[dtgrdn]

It hasn't finished yet when you transfer it. You should take gravity readings with a hydrometer to make sure it's finished before transferring to secondary.

 

[ADancy]

It hasn't finished yet when you transfer it. You should take gravity readings with a hydrometer to make sure it's finished before transferring to secondary.

Instructions I've read were to move it when fermentation slowed, but before it completes. I do take readings, but I haven't been looking for it to be complete before moving to secondary.

 

[dlaramie08]

It possibly could be still fermenting, but most likely you're knocking the residual co2 created during fermentation out of solution. If pitched correctly, most of fermentation should be done in about 3-4 days. You may want to read up on not transferring to secondary. It's unnecessary to say the least.

 

[madscientist451]

When you rack the beer you are probably introducing some air in the beer and that helps jump start the yeast into action. If you leave it in the primary, the yeast will still finish up their work. Too much air in the beer could cause oxidation problems, including stale, off flavors.
If you consume your beer quickly and/or keep it refrigerated when its done, the oxidation issues might not be noticeable. You really don't need to rack to secondary at all. When the beer is done fermenting you can rack to a keg, bottling bucket, or even bottle right from primary. Some beers benefit from bulk aging, in that case racking to secondary is one of your options.

 

[ADancy]

Knocking some CO2 out of solution is a reasonable theory, thanks.

But I've got a honey porter right now still releasing bubbles from the airlock 3 weeks after brew day and 2 weeks after moving to the secondary, so I wouldn't think that's just residual CO2.

I thought maybe I was not getting enough oxygen in the wort at the start and the yeast was getting a slow start, so I've used a diffuser stone on the latest batch. I moved that batch to secondary today and started seeing more activity in the airlock, hence my question.

 

[MattyIce]

Three weeks is much more likely to be co2 coming out of solution than fermentation, with the exception possibly being a big, big beer. My last IIPA had an OG of 1.083 and still reached FG inside of a week.

 

[joshesmusica]

Knocking some CO2 out of solution is a reasonable theory, thanks.

But I've got a honey porter right now still releasing bubbles from the airlock 3 weeks after brew day and 2 weeks after moving to the secondary, so I wouldn't think that's just residual CO2.

I thought maybe I was not getting enough oxygen in the wort at the start and the yeast was getting a slow start, so I've used a diffuser stone on the latest batch. I moved that batch to secondary today and started seeing more activity in the airlock, hence my question.

yeah it's still likely to be CO2 being released. the easiest way to know if this is the case is to check your gravity before racking to secondary (which you should be doing anyways, as i believe you shouldn't be racking until it's reach it's FG). if you're at 1.011 when you rack, then you're still at 1.011 after secondary, then you haven't had any fermentation, and therefore it was just CO2 in the beer.

i do primary only, and therefore dry hop in my primary bucket. i typically wait until anywhere around day 9 or 16 (5 days dry hop, and it depends if i'm leaving for 2 or 3 weeks). even in the ones that i dry hop on day 16, once i dry hop and move into a warmer environment, i always get airlock activity, even though the beer's been done fermenting for quite some time.

 

[progmac]

yes, racking can restart activity. with some strains prone to sticking, wyeast says, "rack or gently stir to finish fermentation."

 

[joshesmusica]

yes, racking can restart activity. with some strains prone to sticking, wyeast says, "rack or gently stir to finish fermentation."

of course, that's with a stuck fermentation. if your beer has reached it's FG there's no amount of rejuvenation that you could do (short of adding a wine yeast or some bacteria) that will restart fermentation activity.