When is a secondary fermenter a good idea?

[jrgtr42]

Personally the only time I use a secondary is if I need to bulk age it, like an imperial stout on wood or brewing a sour where it needs to sit for a long time to develop- mine are a year from grain to bottle.

 

[BrewnWKopperKat]

If the result seems lacking (after three or four months in the bottle) I'll try again and use a secondary.

If you go back to looking at alternatives, this (from #114 in What does a secondary fermenter do? (link)) may be of interest.

You have to understand that [author of reply, not me] [is] a walking time capsule. I quit doing any type of brewing research in 2009. I’ve still brewed 200+ gallons a year since, but using the standard, accepted practices of that era. I got back online 2 weeks ago [Sept 2021] and learned that I was making crappy beer because I use a secondary, don’t purge with co2, yadda, yadda, yadda. I’d be willing to bet most people regurgitating all of this oxygenating stuff have never experienced oxidation, and are just repeating what they have learned as if it was settled science.

The standard theory of 12 years ago was that when you transferred to the secondary, you would get some minimal contact with air, but you keep the output end of the siphon in the beer to minimize splashing. There is some dissolved co2 that gets released during the transfer that blankets the beer. If you aren’t dry hopping, you make sure that your batch is big enough to fill into the neck of the carboy. You are then left with a few cubic inches of air space that will be filled with co2 as fermentation completes.

 

[tracer bullet]

Everyone's got an opinion. I can say factually though that the CO2 blanket is indeed a myth, and in my own experience that once I started paying attention to oxygen and started doing closed transfer my hoppy beers stayed hoppy FAR longer than before. I won't say secondary's are bad, if done properly. But anytime I read about oxidation not actually being a thing, or the words "CO2 blanket" it sure makes it hard to pay attention to anything else that person writes.

My imperials sit in the primary 3, maybe 4 weeks until fermentation is obviously done. Then they go to a keg. Then they sit until they taste good. It doesn't seem complicated. I guess I'd "secondary" if I didn't have a spare keg but did have an extra fermenter, but wouldn't enjoy the extra step nor the associated risks.

 

[BrewnWKopperKat]

But anytime I read about oxidation not actually being a thing, or the words "CO2 blanket" it sure makes it hard to pay attention to anything else that person writes.

Try reading this:

You have to understand that [author of reply, not me] [is] a walking time capsule. I quit doing any type of brewing research in 2009. I’ve still brewed 200+ gallons a year since, but using the standard, accepted practices of that era. I got back online 2 weeks ago [Sept 2021] and learned that I was making crappy beer because I use a secondary, don’t purge with co2, yadda, yadda, yadda. I’d be willing to bet most people regurgitating all of this oxygenating stuff have never experienced oxidation, and are just repeating what they have learned as if it was settled science.

The standard theory of 12 years ago was that when you transferred to the secondary, you would get some minimal contact with air, but you keep the output end of the siphon in the beer to minimize splashing. [...] If you aren’t dry hopping, you make sure that your batch is big enough to fill into the neck of the carboy. You are then left with a few cubic inches of air space that will be filled with co2 as fermentation completes.

Also note that what's being quoted doesn't apply to those who keg. The discussion and ideas may, however, be useful for people who use carboys, bottle condition, ...

 

[tracer bullet]

Try reading this:

I did, and was primarily replying to it - "oxygenating stuff", "CO2... blankets the beer". The first is real, the second is not, certainly from my experience and most others. Certainly not all, but much or most, of what we all do today is based on reality.

 

[BAF]

The only times I've used secondaries have been for fruit additions (getting an actual secondary fermentation) and once for an imperial stout (just to help clarify more and drop more yeast out). Probably not super necessary in either case, but I have the ability to do closed transfers, so I didn't mind it.

If you're going to transfer to secondary just for the sake of it, and not even add wood additions or anything, then I would definitely skip it. Let it sit in primary longer if you want to bulk condition, and then bottle when you're happy. I've done other stouts and left the beer in primary for well over a month with no ill effects. I'm firmly on the bandwagon of autolysis not being a concern on the homebrewing scale, and would not recommend moving to secondary simply to "get the beer off the yeast" -- especially if you cannot do a closed transfer.

 

[BrewnWKopperKat]

I did, and was primarily replying to it - "oxygenating stuff", "CO2... blankets the beer". The first is real, the second is not, certainly from my experience and most others. Certainly not all, but much or most, of what we all do today is based on reality.

FWIW, In this section ...

make sure that your batch is big enough to fill into the neck of the carboy. You are then left with a few cubic inches of air space that will be filled with co2 as fermentation completes.

... there is a concept that was also used when bottling NEIPAs that stay fresh in the the bottle a long time.

 

[tracer bullet]

FWIW, In this section ...

... there is a concept that was also used when bottling NEIPAs that stay fresh in the the bottle a long time.

Agreed to fill up bottles, yes. Doing it with carboys may be less realistic but I guess if you plan ahead you might stuff a 6.5 gallon brew into a 5 gallon carboy. Sorry I was commenting on all the rest. This part I agree is a good practice if you can get it done.

 

[z-bob]

Agreed to fill up bottles, yes. Doing it with carboys may be less realistic but I guess if you plan ahead you might stuff a 6.5 gallon brew into a 5 gallon carboy. Sorry I was commenting on all the rest. This part I agree is a good practice if you can get it done.

If you're a little bit short of filling a carboy, you can top up the beer with a deoxygenated water, or a flavorless beer like Keystone Light. (I'd probably use Natural Ice.) In 5 gallons, it's not going to make a noticeable difference but it will displace that much air and you'll get one more bottle of HB on the back end.

 

[pc_trott]

"oxygenating stuff", "CO2... blankets the beer". The first is real, the second is not

Keep in mind that I got my science degree from a vending machine at Walmart, but I've seen this suggestion several times, and it does not seem logical. Say, for argument, that you have a cubic foot of space in the top of your carboy, under an airlock. There is a mixture of air in it; oxygen, nitrogen, carbon dioxide, etc. The only gas that is being replicated is carbon dioxide, as the still working yeast produce it. The carbon dioxide is expressed at the top of the wort, increasing the percentage of carbon dioxide in the headspace. The increased gas pushes upward, and expels an equal amount of gas out of the airlock. There are no air currents or disturbances in the carboy to mix the "air" with the pure carbon dioxide, so it stands to reason that eventually, all of the oxygen, nitrogen, etc., will be lifted up and expelled from the fermenter, leaving only carbon dioxide, as long as the yeast keeps working.

Again, I readily admit that this suggestion is worth what you paid for it.

 

[McMullan]

A quick sniff of the exhaust gas from an FV, including a secondary being filled, is usually enough to reveal a CO2 blanket. It's why actively fermenting wort can be sprayed to rouse yeast in a Yorkshire square, without negative effects of oxidation. In my experience, CO2 blankets are pretty stable. At the end of fermentation the beer is saturated with CO2. Some of this CO2 is released during transfer, forming a new CO2 blanket. However, it's good practice to purge air from the secondary vessel, e.g., using CO2 from fermentation in the primary, which has been recommended for years. Ironically, in terms of air/O2, we just did a 'traditional' closed transfer. Ta-da! I do wonder if the perceived risk of transferring to a secondary vessel is driven by fashions for making increasingly hoppier beers, which are more vulnerable to oxidation during transfers, especially when good practices aren't being followed. It might be the case for modern IPAs that avoiding a secondary is best practice, but this doesn't translate into 'secondaries are a myth and unnecessary'.

Once fermentation's done, and yeast metabolism changes, there's no benefit in keeping the beer on the yeast. As CO2 bubbles from residual yeast activity erupt from the slurry, yeast and trub get dragged back into suspension, slowing clearing and potentially risking introduction of off flavours. It's good practice to get beer off the yeast to stabilise the product as soon as possible. It's the home brewer's individual choice whether he or she follows good practices. Regardless, personal opinions and preferences aren't going to prove good practices wrong. Following good practices just increases the probability of success. I bet there's a correlation between following good practices and award-winning beer, but I doubt we collect enough information to show it.

 

[BrewnWKopperKat]

I'm firmly [of the opinion that] autolysis [is not] a concern on the homebrewing scale

Everyone tastes beer differently (The New IPA, chapter 5, first couple of paragraphs). Anecdotally, some people appear to be very sensitive to the off flavors that come from autolysis (see the various strong opinions in Homebrew All-Stars).

FWIW, I have experienced the off-flavors associated with autolysis (in a commercial craft beer).

Learn to identify off flavors, learn the process step(s) where the off flavors can come from, adjust the process to remove the off flavors.

 

[tracer bullet]

If CO2 blankets were real, we'd all be living on mountain tops so we wouldn't suffocate. CO2 will be more prevalent for some tiny amount of distance if it's actively coming out of the beer while it's fermenting. But it mixes, uniformly, after a short time, with whatever is int he headspace above it. Even if it's not actively stirred up. Including any oxygen if present. Oxygen is eventually pushed out not because it's lighter and sits on top, but because it's part of the mixture coming out and eventually it's simply diluted to the point it doesn't matter any more.

 

[schmurf]

If CO2 blankets were real, we'd all be living on mountain tops so we wouldn't suffocate. CO2 will be more prevalent for some tiny amount of distance if it's actively coming out of the beer while it's fermenting. But it mixes, uniformly, after a short time, with whatever is int he headspace above it. Even if it's not actively stirred up. Including any oxygen if present. Oxygen is eventually pushed out not because it's lighter and sits on top, but because it's part of the mixture coming out and eventually it's simply diluted to the point it doesn't matter any more.

I'm not going to argue about whether co2 blankets exists or not, I'm too uneducated about it, but in my mind comparing the environment in a fermenter and open air is a bit wrong. I'm thinking of climate, wind etc.

 

[BrewnWKopperKat]

Ideally one wants more of the beer friendly blue dots (CO2) than the beer hating red dots (O2).

 

[tracer bullet]

I'm too uneducated about it.

That's OK, and questions are good. But it's been established science for centuries that gasses mix and do so quite on their own. I'm sure wind speeds things up for us breathing but even in a dead still fermenter, head space gasses most definitely do not striate and anything that manages to outgass into it from the beer below does not create a blanket that sticks around for any appreciable amount of time.

I've used a helium detector (to check for leaks in hermetically sealed medical devices) and watched helium be detected when it flowed upstream of a duct with a fan pushing air through it. Not even that moving air could stop it from mixing in faster than the air was flowing.

The CO2 blanket thing, while plausible, is not real. Feel free to look into it, and if you can find a single peer reviewed paper that says anything other than gasses spontaneously mix with each other, I'd be very interested.

 

[McMullan]

If CO2 blankets were real, we'd all be living on mountain tops so we wouldn't suffocate. CO2 will be more prevalent for some tiny amount of distance if it's actively coming out of the beer while it's fermenting. But it mixes, uniformly, after a short time, with whatever is int he headspace above it. Even if it's not actively stirred up. Including any oxygen if present. Oxygen is eventually pushed out not because it's lighter and sits on top, but because it's part of the mixture coming out and eventually it's simply diluted to the point it doesn't matter any more.

Sorry, but that expresses far too much ignorance about atmospheric processes which mix air. E.g. pressure differences, low to high, governed by differential temperatures. Like wind? Were it not for these processes your reasoning might hold true and life on Earth would never have evolved.

 

[McMullan]

Ideally one wants more of the beer friendly blue dots (CO2) than the beer hating red dots (O2).

Does that square border represent the wall (barrier) of an FV? Just asking for a friend.

 

[tracer bullet]

Were it not for these processes your reasoning might hold true and life on Earth would never have evolved.

It appears we are saying the same thing. What do you not agree with?

 

[McMullan]

If CO2 blankets were real, we'd all be living on mountain tops so we wouldn't suffocate.

It appears we are saying the same thing.

The complete opposite, actually.

What do you not agree with?

Artificial order, textbook models and vacuums that only exist in minds. Nature is disorder and chaos, in reality. And we‘re products of it, struggling to understand artificial order

 

[z-bob]

CO2 blanket is real, but it doesn't really protect all that much from oxygen unless enough new CO2 is being produced to replenish the blanket faster than the O2 diffuses in. As in, an actual "air" current flowing away from the surface of the liquid. (I might be fooling myself about CO2 replenishing faster than O2 diffuses in; I don't know the rates.) A layer of bubbles or foam should make a good barrier, until it collapses.

Gases mix all on their own due to something called "partial pressure". Otherwise we wouldn't need air locks.

 

[McMullan]

Partial pressure based on what, textbook models that assume homogeneous space, a vacuum? Neither the world (nature) nor the artificial (closed) environments of our active FVs are that ordered. What you’re saying really, @z-bob, ironically, is something more like, ‘get the beer off the yeast as soon as’. The belief that gases spontaneously find order universally at the drop of a hat (all other things being unequal) is a little bit funny.

 

[z-bob]

All I'm saying is the CO2 blanket on top of the fermenter is unreliable. I didn't say it wasn't there; quite the contrary. It doesn't stop oxygen, only slows it down; the O2 will infiltrate your blanket. (so will nitrogen, but we don't care about that)

 

[McMullan]

Eventually, yes. Hence why you recommend ‘getting the beer off the yeast as soon as’. I like it. It makes so much sense

 

[tracer bullet]

OK, 'cause your earlier post made no sense. That if it weren't for wind, maybe my proposal of gasses mixing on their own could actually be real. Or something. So, anyhow, you're a firm believer in CO2 blankets? I think. Even while you say at the same time there's disorder and chaos in reality, and that having no headpsace or purging it is a good idea.

OK, I guess. I can move on.

 

[McMullan]

OK, 'cause your earlier post made no sense. That if it weren't for wind, maybe my proposal of gasses mixing on their own could actually be real. Or something. So, anyhow, you're a firm believer in CO2 blankets? I think. Even while you say at the same time there's disorder and chaos in reality, and that having no headpsace or purging it is a good idea.

OK, I guess. I can move on.

There are no valid comparisons between your model and the real world, be it on top of a mountain or inside a fermenter.

 

[SFC Rudy]

Q: When is a secondary fermenter a good idea?

A: When you want to do it. You do you, if it works for you, great! If not, well you learned something.

Remember this; in this hobby no matter what you do someone will lose their mud because you're not doing it exactly how they are doing it.

 

[tracer bullet]

Sorry, but that expresses far too much ignorance

exist in minds

your model

You have an interesting mind, I think. You keep refuting that gasses mix, then go on to describe why gasses certainly mix. I'm not trying to win here, I'm just trying to figure you out. Gas mixing has been well established for perhaps hundreds of years, a long time anyhow. It's not my model, nor ignorant. I think you maintain a CO2 blanket is real, and at the same time say that gasses go nuts and mix like crazy even inside fermenters.

Sorry to everyone else, I'm just curious to figure this out. If it should be deleted I certainly understand.

 

[McMullan]

You have an interesting mind, I think. You keep refuting that gasses mix, then go on to describe why gasses certainly mix. I'm not trying to win here, I'm just trying to figure you out. Gas mixing has been well established for perhaps hundreds of years, a long time anyhow. It's not my model, nor ignorant. I think you maintain a CO2 blanket is real, and at the same time say that gasses go nuts and mix like crazy even inside fermenters.

Sorry to everyone else, I'm just curious to figure this out. If it should be deleted I certainly understand.

I haven't refuted anything. Just pointed out how it doesn't work as you imagine, in the real world. One of the reasons I try to avoid active volcanic craters. The blanket of toxic gases. Ditto smogs and other air pollution events, which tend to linger in calm (FV like) conditions, especially in the city, where high levels of pollution get generated then trapped for hours, days or even weeks.

 

[Bobby_M]

Brewing under rules of democracy? Interesting.

There are definitely occasions when a secondary is useful, or even required, if you can be bothered and you have the basic skills required to prevent oxidation during transfer. E.g., if you need the beer to be ready sooner, which is why commercial breweries often use settling tanks after fermentation is done; and, ironically, why home brewers get so excited about conicals, which become secondaries once the yeast cone gets dumped. And long-term ageing of big beers, of course. The idea green beer is fine sitting on the yeast for weeks or longer is not always true. It assumes the yeast are healthy. In some cases high levels of yeast autolysis risk transforming beer into drain water.

I guess all comments need to be carefully crafted. I made a blanket statement that most people don't do it anymore and I skipped over the part where those people have good reasons.

If one does not have a way to effectively mitigate oxygen exposure during a transfer, that transfer should be avoided if possible. When faced with the option of transferring to an unpurged second vessel or bottling and aging there, I recommend bottling.

Even when using a conical, which effectively becomes a bulk aging tank after dumping as much yeast as you can, a source of CO2 is all but required for the same oxygen exposure reasons.