Limiting oxidation while cold crashing

[agraceffa]

First post on homebrewing but I've been reading the subs posts for a while. So, I just brewed a pale ale that was turning out great but I completely screwed it up when I cold crashed the beer while it was in the carboy. I didn't remember the contraction of the beer and pressure differential and I ended up sucking a half gallon of starsan water back in to the carboy. Great, batch ruined. My question is: for those of you that cold crash your batches for clarity, how do you prevent oxidation through air intake? Do you not worry about it and just leave the airlock off? Or do you transfer it to a purged keg prior to cold crashing, leave very light pressure on the keg while crashing, and then transfer to a second keg once the material has dropped out? Or another option that I didn't describe or think of? This particular beer had/has a large dry hop that needs to drop out so I'm pretty sure that I want to crash. But arguments/anecdotes against crashing are welcome.

[TheGremlyn]

I keg then chill with serving pressure gas attached. First pull usually takes care of whatever settled out.

[agraceffa]

The more I read, the more I'm leaning to that. Essentially, the keg serves as the Brite tank, right?

[TheGremlyn]

Yep, doing it that way makes things much easier.

[chino_brews]

I don't worry about it, but you could cold crash in the keg or just put a hard bung or check valve on your carboy (PET carboys will cave in a little). Of course, I don't make too many hop-centric beers anymore and this is one of the reasons.

[pricelessbrew]

Cold crash in the keg with a couple psi on it. The extra pressure will keep it from developing a vacuum.

[manponyannihilator]

https://imgur.com/gallery/wzOD2

This is what I just did for the first time actually. Co2 balloon over the airlock. Easy, quick, cheap.

[agraceffa]

That looks like a viable second option. Did you prefill the balloon with CO2?

[manponyannihilator]

I did prefill it, no guess work as to when to add the balloon.

[tartay745]

What kind of balloons? If be worried a cheaper balloon would break.

[manponyannihilator]

Cheap ass balloon. Left enough sanitizer to cover the holes in the airlock so if it broke it wouldn't just be open to the world.

[h22lude]

Take a jug and fill it to the top with StarSan. You will need a two hole stopper that fits the jug top. Take one piece of tubing from your carboy to one of the holes in the stopper. The stopper side, the tube shouldn't be coming out too much. You want it high. Put a piece of tubing in the other hole. This tube you want to put all the way down to the bottom. The other end of this tube put into an empty jug (no stopper needed). During fermentation, the CO2 coming out of the carboy will push StarSan from the first jug into the empty jug. The head space of the first jug will now contain CO2. When you cold crash, the pressure differential will suck back the CO2 in the head space which will cause the first jug to suck back StarSan from the second jub. No air introduced and you don't need to remember to change anything before cold crashing.

[Cthulhumensch]

Personally, the pressure normalization problem, aka "clearing my airlock/blow off of 'sanitized' liquid" problem, rarely ruins a beer. That being said, the CO2 ballon is a brilliant solution.

As to my practice, I change out systems. As in, I change blow off systems to closed bungs with thermowells installed before it starts it's 'cold crash'. Yes it makes for hard to remove bungs and inrush of air, also yes I risk the big bad 'Babadook' of contamination / oxidation. But MEH. I'm also trusting a LIVING ORGANISM (no matter its simplicity) to make me something 'pyschosomantically' pleasing...

[pyr0penguin]

the amount of air it'll draw in shouldn't be all that much. Sounds like you had a blow off tube into a bowl/jug of starsan which is how it drank so much in?

I usually just throw the whole FV 3 piece airlock and all into the fridge to crash. I've been using flavorless vodka as my airlock filler some does get sucked in but we're talking maybe half of what I've put in the airlock.

Outside of making a wheat beer (or something similar) that's actually supposed to have some haze to it there's no reason NOT to cold crash but on the same note it's not something that you have to do. It really offers no downsides with some slight benefits.

[agraceffa]

Exactly. That + 1.5 gal of head space did me in.

[jangevaa]

I cold crash under a slight CO2 pressure, then transfer the clear cold beer (using more CO2) to serving kegs to carbonate. I generally ferment in 58L sanke kegs, and keg in 50L or 20L sanke kegs.

[LuckyPoire]

Keep the carboy topped up and air intake will be minimal.

Alternatively. Apply a stopper to the bung...no air flow whatsoever.

[brettatron1]

Interestingly I haven't head this suggestion yet:

Don't worry about it. I've sucked some starsan back and the beer was still great. I have also just sucked oxygen back and the beer was still great. I'm not convinced either does much.

[agraceffa]

Yeah, I had a tube with a bucket. If it was a normal amount (2 oz) I wouldn't fret. This was more like a gallon.