Cold crash, air lock sucking

[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.