Help! - Cold crashed and sucked back blow off liquid...

[CRBrewHound]

A one-piece airlock will not allow the vacuum to suck liquid back in.

Umm, yes it will.

It depends on draw pressure placed by the change in temp and how quickly it occurs, just like you can get blow off and clogging of those it can do the same in reverse.

All airlocks and blow off systems work on the system principles. pushing the CO2 through a steril liquid medium to prevent the introduction of bacteria and wild yeast through the air. The problem with all of them is that they can only handle a certain capacity of flow and when the flow is exceeded they pull or push liquid instead.

[Elbone]

A one-piece airlock will not allow the vacuum to suck liquid back in.

Umm, yes it will.

It depends on draw pressure placed by the change in temp and how quickly it occurs, just like you can get blow off and clogging of those it can do the same in reverse.

All airlocks and blow off systems work on the system principles. pushing the CO2 through a steril liquid medium to prevent the introduction of bacteria and wild yeast through the air. The problem with all of them is that they can only handle a certain capacity of flow and when the flow is exceeded they pull or push liquid instead.

Umm, no it won't. If you don't overfill it. It will bubble before liquid can get over the top bend in the tube, breaking the vacuum. You might get a drop or 2 of liquid from splashing, but you cannot suck the contents of the airlock into the fermenter. Try it.

[animaldoc]

Ok, this is something I never understood .... enlighten a brotha please.

Why are we putting blow-off tubes into liquid? What is the benefit of "bubbling" thru star san??

Put the blow-off tube into the growler so that blow-off is contained by the growler (or other container) such that the liquid level stays away from the opening of the tube. Bacteria and wild yeast are not going to climb up the blowoff tube. Positive pressure from CO2 generation will keep oxygen from diffusing up into the carboy.

When rapid fermentation starts to subside, replace the blowoff tube with an airlock. As CO2 production subsides further, you are in a closed environment.

Any time you cool the fermenter you will generate a lower pressure inside the carboy .... as previously stated, reducing the headspace will minimize but not eliminate the effect .... running the risk of "suck back"

Am I missing something? Minimizing the importance of something?

[HoozierDaddy]

At the end of the day it comes down to: Is cold crashing necessary in the fermenter? I say no. If you cold crash in the fermenter, you WILL pull in something into that fermenter that would not have been had you left it the hell alone. I had to learn this the hard way as well.

Why cold crash? Clarity? Let the fermenter sit a bit longer and that should solve that. Or cold crash in a sealed keg; no way for anything to get sucked into your beer there either.

[Elbone]

I'll cold-crash when I'm planning to add gelatin to the keg. Gelatin seems to be more effective at cold temps, so I'll cold-crash the primary for a couple of days to get the beer as clear as I can, then rack into the keg onto some gelatin. I guess I mainly do it to speed up the conditioning process so I can drink it faster. It's absolutely not necessary- time will handle it. Time + cold temps will handle it faster, time + temp + gelatin will handle it even faster. I'm an impatient brewer.

Last year I had a gorgeous BGS in the primary that had finished after about 3 weeks. I decided it was time to cold-crash as I walked by the fermentation fridge and just adjusted the controller down to 35. I forgot I still had a blow-off tube attached sitting in a quart of blowoff, yeast, dead fruit flies and God only knows what else. I won't make that mistake again.

[keelanfish]

At the end of the day it comes down to: Is cold crashing necessary in the fermenter? I say no. If you cold crash in the fermenter, you WILL pull in something into that fermenter that would not have been had you left it the hell alone. I had to learn this the hard way as well.

Why cold crash? Clarity? Let the fermenter sit a bit longer and that should solve that. Or cold crash in a sealed keg; no way for anything to get sucked into your beer there either.

Well, I don't keg and unfortunately still bottle and bottle condition. So, the reason I cold crash in the fermenter is to avoid an additional transfer to a bright tank. I like to settle out as much as I can, and also firm up the trub so I don't pick up too much during the transfer to bottling bucket.

[slyinski]

Just started reading forum so I'm a little late to this thread but... I basically have the same problem and i use either a small air filter bought at Morebeer or the chemist (S shaped) airlock to prevent liquid from being sucked back in. My worry about the vacuum created is not infection but oxidation from sucking air into the fermentor. Is that something to worry about or am i over thinking it. I usually transfer to the keg after terminal gravity is reached plus about 3-4 days, cold crash in a keg that the dip tube has been shortened and let age however long is appropriate for the beer, then transfer to serving keg. Would love some feedback and any suggestions on what other ppl do.

[Bad Goat Brewing]

Just started reading forum so I'm a little late to this thread but... I basically have the same problem and i use either a small air filter bought at Morebeer or the chemist (S shaped) airlock to prevent liquid from being sucked back in. My worry about the vacuum created is not infection but oxidation from sucking air into the fermentor. Is that something to worry about or am i over thinking it. I usually transfer to the keg after terminal gravity is reached plus about 3-4 days, cold crash in a keg that the dip tube has been shortened and let age however long is appropriate for the beer, then transfer to serving keg. Would love some feedback and any suggestions on what other ppl do.

This thread had a good discussion about oxidation. I think most people don't worry about it, but I'm sure it doesn't help the beer.

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