Avoiding cold crash O2 suckback

[RPh_Guy]

I have never noticed any liquid being sucked into my fermentors before. Are people saying this is worse when using a blow off tube?

3-piece airlocks and blow-off tubes may suck in liquid. That's relatively easy to avoid. The more complicated problem is preventing oxygen from getting inside.

All these plastic or silicone devices that prevent air getting in still let through a lot of oxygen.
They probably help to some degree, but it'd be like using a blow-off that only sucks in a few cups of sanitizer instead of a gallon.

 

[pretzelb]

If you're using a brew bucket ... no reason to get fancy. Ss Brewtech clearly lists what you need to handle cold crashing and pressurized transfers.

Here's a picture of both active fermentation and cold crashing.

Looking at this picture again, why is only one line going out from co2 and only one going to the blow off? Are these daisy chain so both co2 input and blow off are linked?

 

[Brewtallica]

The suck back is about 2 liters in my experience. No hose is big enough. This works. https://www.brewhardware.com/product_p/ccguardianv2.htm

I've had great success with the Cold Crash Guardian. I modified it by using a CO2 tee fitting I had laying around.
https://www.morebeer.com/products/co2-tee-stainless-steel.html
It now has a better seal than the plastic one that came with it. I also extended the tube that connects to the bag so I can move it around the fermentation freezer.

 

[Jtvann]

Looking at this picture again, why is only one line going out from co2 and only one going to the blow off? Are these daisy chain so both co2 input and blow off are linked?

Only one is being cold crashed. The other is still fermenting. They are two separate systems.

 

[pretzelb]

Only one is being cold crashed. The other is still fermenting. They are two separate systems.

I'm an idiot. If I just looked at the different temps I could have figured that out. So you just unhook the blowoff and add co2 at low pressure? Interesting.

 

[Jtvann]

I'm an idiot. If I just looked at the different temps I could have figured that out. So you just unhook the blowoff and add co2 at low pressure? Interesting.

I usually hook up CO2 at the same time I drop hop, or just a few points above final gravity. If any pressure does build up, theres a pressure release valve to vent. It's just important to be beyond any possible blow off.

I don't leave the tank on all the time. I turn it on until the lid blows up from pressure, then turn it off. I check it periodically while crashing and reinflate as needed. It's really easy to waste an entire CO2 cylinder if you leave it on all the time. Once you hit 35, or whatever your fresh temp is, there's no more suck back.