Cold crash, air lock sucking

[Bobby_M]

The cold crash suckback has always bothered me and I've never accepted the recommendations not to worry about the air that comes back into the fermenter. It absolutely is an oxidation risk and as you've seen, the liquid in either airlocks or blowoff containers will get into the beer if you're not careful.

My current solution, that I haven't implemented or tested yet is to run the blowoff hose into a soft "cubetainer" in an air tight way. Also installed in that container is a silicone no-liquid airlock. As you're fermenting, CO2 fills the container to capacity and starts dumping through the flapper style airlock. When it's done, the container is full of CO2. Cold crash and in theory, the only thing that goes back into the fermenter is the CO2.

 

[IL1kebeer]

the cold crash suckback has always bothered me and i've never accepted the recommendations not to worry about the air that comes back into the fermenter. It absolutely is an oxidation risk and as you've seen, the liquid in either airlocks or blowoff containers will get into the beer if you're not careful.

+1

 

[AnOldUR]

?

More co2 goes into solution as the temperature of the beer drops. This should mean that the some of co2 in the headspace will be absorbed by the colder beer until an equilibrium is reached. This is why kegs are better carbonated cold and not at fermenting or room temps. Am I understanding this incorrectly? ]

Sorry, that was a drunken post last night.

My interpolation is that there is no CO2 blanket. That gasses readily mix, so any O2 entering the fermenter will dilute the CO2 that’s present. My understanding is that CO2 absorbsion is a factor of temperature and pressure. Since the only pressure in your fermenter is atmospheric, whatever CO2 is present will not be forced into suspension just because there’s a temperature drop. At the point that you’ll be cold crashing there is already CO2 remaining in suspension. If what you suggest is true, an open bottle of beer in your refrigerator would never go flat or oxidize. A layer of CO2 coming out of suspension would blanket the surface and protect your beer. That’s never worked for me.

I have tried the silicone stoppers that Bobby mentioned, but my normal solution is to remove my carboy cap and immediately cover the top with foil and a tight rubber band. This is assuming that the only gas present in the carboy at that time is CO2 and that the quick process and small opening will minimize any exchange of gasses. In a situation of cold crashing a secondary, the small amount of surface area exposed combined with this technique helps me sleep at night.

But I could just be fooling myself.

Oh, and what you said about better to carbonate a keg cold. Not so sure about that either. If you set the pressure for the volumes of CO2 you're looking to get into your beer, I believe it will actually absorb faster at the higher temperature. Something about the speed that the molecules move around at. It’s just that it take less pressure to carbonate cold (not actually less CO2 though) and you won’t have to wait for your beer to chill before drinking.

Cold Crashing Primaries. . .

 

[solbes]

If you have the vertical space in your fridge, why not use one of these? I have never had suck back when using these, but always do when using a 3 piece.

Now it won't filter your air and it won't prevent oxygen from getting in when the liquid volume is decreasing. Kegs are a solution to the oxidation, but negate the very benefit of cold crashing. Not sure I would want to put any positive or negative pressure on a glass carboy.

 

[IL1kebeer]

My interpolation is that there is no CO2 blanket. That gasses readily mix, so any O2 entering the fermenter will dilute the CO2 that’s present. My understanding is that CO2 absorbsion is a factor of temperature and pressure. Since the only pressure in your fermenter is at.

I agree with that but it's such a huge myth that I didn't want to open that can of worms. I felt that it bad enough that I was already bad mouthing cold crashing. It would have been even more blasphemy if I went against the co2 blanket as well.

Oh, and what you said about better to carbonate a keg cold. Not so sure about that either. If you set the pressure for the volumes of CO2 you're looking to get into your beer, I believe it will actually absorb faster at the higher temperature. Something about the speed that the molecules move around at. It’s just that it take less pressure to carbonate cold (not actually less CO2 though) and you won’t have to wait for your beer to chill before drinking

Kinds getting off topic but you can carbonate a keg at any temperature you please. I believe that it's better cold since you use less co2.

 

[IL1kebeer]

Kegs are a solution to the oxidation, but negate the very benefit of cold crashing.

Not entirely true. I know that it's more work but you can transfer to a fresh keg after the period of cold conditioning and leave all the crud behind. That's really unnecessary though since only the first pint or two will be cloudy. I just leave it in the initial keg and have really clear beer after cold conditioning without the risk of oxidation.

 

[AnOldUR]

Kinds getting off topic but you can carbonate a keg at any temperature you please. I believe that it's better cold since you use less co2.

It takes more pressure to get the same volume of CO2 into suspension in warm beer, but it's still the same amount of CO2. You don't use less because you forced it in cold.

That's really unnecessary though since only the first pint or two will be cloudy. I just leave it in the initial keg and have really clear beer after cold conditioning without the risk of oxidation.

But if you don't transfer into a different serving vessle, it's not really cold crashing. So, what you're saying is that cold crashing is not necessary if you're kegging?

 

[solbes]

Not entirely true. I know that it's more work but you can transfer to a fresh keg after the period of cold conditioning and leave all the crud behind. That's really unnecessary though since only the first pint or two will be cloudy. I just leave it in the initial keg and have really clear beer after cold conditioning without the risk of oxidation.

Mmm hmm, but the benefit of cold crashing is to avoid racking and drop most of the yeast in primary. If you rack to a keg used as a brite tank, you will still need to rack out of it to package. I have never used a keg as a brite tank for ales as I either cold crash or rack to a room temp carboy. Most of the yeast drops out in 24 hours when racked to room temp carboy.

Also agree with above on CO2 vs beer temp. Higher pressure is needed to carbonate warm beer, but it will still require the same amount of CO2.

 

[IL1kebeer]

But if you don't transfer into a different serving vessle, it's not really cold crashing. So, what you're saying is that cold crashing is not necessary if you're kegging?

In my experience, you will get the same result. After period of cold conditioning in a keg, all of the crud will drop to the bottom and your beer will be clear as day after the first pint or two. This also prevents sucking in oxygen while cold crashing in a carboy or bucket. Of course you still should be careful when you rack so you don't unnecessarily siphon a bunch of crud or dryhops or whatever, but again it should settle out anyway and you just might have a few more cloudy pints. If I'm going to fill a case with my beergun I cold condition for a week or two and then drink the first few pints. Everything after that is nice and clear and really to be bottled. In addition to myself believing that I have clear beer, I also haven't lost points in competition for appearance with this method, even with dryhopped beers.

A lot of other brewers skip cold crashing in the fermenter in favor of cold conditioning in the keg and report good results.

 

[TAK]

How about this....

Put a splash of starsan in a 2 liter soda bottle and fill the rest with CO2 via a carbonator cap, at 0-1 PSI. Then replace your airlock with a tube that's capped off with a ball lock disconnect. Lastly, attach that to the soda bottle and cold crash. The soda bottle will take the negative pressure and the only thing that will go back into the carboy is CO2.

 

[TrojanAnteater]

The cold crash suckback has always bothered me and I've never accepted the recommendations not to worry about the air that comes back into the fermenter. It absolutely is an oxidation risk and as you've seen, the liquid in either airlocks or blowoff containers will get into the beer if you're not careful.

This EXACTLY. I just got back into brewing after a little hiatus, first 2 batches were fantastic, the second two, TERRIBLE. Major oxidation. What did I do differently? I cold crashed. Lots of suckback, of course. Granted, my batches were 3 gallons in a 6 gallon carboy, so there was A LOT of headspace. This probably made it worse, but those two batches were so stale and undrinkable about 2-3 weeks into bottle conditioning/carbonating. I'm 99% sure it was due to trying to cold crash, especially in a carboy with too much headspace.

 

[fantomlord]

How about this....

Put a splash of starsan in a 2 liter soda bottle and fill the rest with CO2 via a carbonator cap, at 0-1 PSI. Then replace your airlock with a tube that's capped off with a ball lock disconnect. Lastly, attach that to the soda bottle and cold crash. The soda bottle will take the negative pressure and the only thing that will go back into the carboy is CO2.

this sounds like a good idea...minus the splash of starsan. I'm not sure it serves any purpose. I would just sanitize, then backfill/pressurize with CO2, and hook it up.

 

[mbbransc]

If worried about oxidation, hook up CO2 to the blowoff hose.

If worried about contamination, dip a rag in Starsan and place over the hole.

 

[TAK]

this sounds like a good idea...minus the splash of starsan. I'm not sure it serves any purpose. I would just sanitize, then backfill/pressurize with CO2, and hook it up.

Been a while since that post, but I think the reason I was thinking about having some StarSan in the bottle is because you can't completely squash a water bottle and get rid of all the air, but if there's just enough StarSan in there, you can push out all the air until it's only liquid left, then fill back with CO2.

I never ended up doing this though. I just crash in a kegs now and there's no contamination risk or oxidation risk.

 

[Bobby_M]

The solution I came up with, but haven't tested yet, is to put a nylon hose barb tee inline from the fermenter to the jar of star san (typical blowoff airlock). The side port of the tee goes to a mylar food storage bag (2 gallon capacity or so). Primary fermentation will first inflate the mylar bag with CO2 and then when it's full, it will push excess out through the starsan jug. When you cold crash, it will suck back the CO2 in the mylar bag until it equalizes. No sanitation risk, no oxidation.

 

[fantomlord]

The solution I came up with, but haven't tested yet, is to put a nylon hose barb tee inline from the fermenter to the jar of star san (typical blowoff airlock). The side port of the tee goes to a mylar food storage bag (2 gallon capacity or so). Primary fermentation will first inflate the mylar bag with CO2 and then when it's full, it will push excess out through the starsan jug. When you cold crash, it will suck back the CO2 in the mylar bag until it equalizes. No sanitation risk, no oxidation.

creative.

how do you plan to seal the mylar bag so it doesn't leak?

 

[TAK]

Maybe you could use a sanitized ballon.

One thing worth considering, though, is for a while the blow off is a mix of newly produced CO2 and the air/O2 that was in the headspace to start.

 

[g8eleven]

Best easy fix I have come up with for the suck-back problem is use your 3 piece airlock like normal (fully assembled with liquid) then stretch a sanitized balloon with a small hole poked in it over the top. Worked for me so far😜

 

[OhSoHumuLonely]

I don't see how you avoid liquid entering that way. I could are a balloon with no liquid, though, if it's big enough.

 

[g8eleven]

The deflated balloon acts as a collapsed diaphragm so to speak. The hole in the balloon is very small so it slowly lets air escape but as soon as you get the suction back into the carboy the balloon collapses at the throat. IMHO this works best when you cap the carboy and chill it down close to the target temp, then install the airlock. Just my opinion.

 

[Brewhunny]

SaWeet!!!!!!

 

[christpuncher123]

Don't pull the tube out of the container! If the container with the sanitizing solution is low enough the suction in the carboy won't pull the solution up the tube high enough to enter the carboy!

 

[GJOCONNELL]

my takeaway from this is use S airlocks and be done with it!

 

[flattie]

Is there any reason you couldn't remove the cap in a 3 piece airlock and stretch a balloon over the top. Then fill the airlock from the bottom with Co2 to inflate the balloon. Quickly replace the airlock in your carboy/ale pail and you now have a balloon full of Co2 so any suck back draws in the Co2.

 

[glugglug]

Has anyone tried cold crashing in a keg and putting co2 at a very low pressure like 2 psi into the gas in? Thinking about a mini co2 regulator with a 16 gram co2 cartridge.

 

[MidAtlanticBrew]

You right that it's a function of temp and pressure but your conclusion isn't correct. Just look at a carbonation chart. If you hold pressure of beer steady while cooling it, it will draw more CO2 into solution.

My understanding is that CO2 absorbsion is a factor of temperature and pressure. Since the only pressure in your fermenter is atmospheric, whatever CO2 is present will not be forced into suspension just because there’s a temperature drop. At the point that you’ll be cold crashing there is already CO2 remaining in suspension. . .

 

[drunkinThailand]

i use the idea from a bong and do what i hope mitigates (i'm not sure enough to say eliminates) both suck back of sanitizer and sucking in oxygen, based on my many years of smoking bongs.

rig up a big (gallon or bigger) water bottle with two holes in the lid, and a piece of rubber tubing going down from one hole into some sanitizer/vodka/etc. during fermentation put a blow off in the fermentor connected to that hose and an airlock in the other hole - this is to hopefully (not sure if it actually works) fill the jug with the CO2 produced during fermentation.

then during cold crash, take off the air lock, move the blow off tube into the vacated hole. now you will suck in the CO2 in the bottle, and oxygen will be sucked in through the other hole/tube/sanitizer, much like a bong. and just like a bong when you don't get water in your mouth, you won't get sanitizer in your beer.

and i know the incoming oxygen (replacing the CO2 you suck back into the fermenter) will mix with the CO2 so you won't be sucking in pure CO2, but i try to open my fermentation chamber as little as possible and as gently as possible so hopefully there's a lot of CO2 and not much oxygen.

another benefit of many years of bong smoking.