Cold Crash Conundrum

[ScottK]

I ferment in a Sanke keg using a blow off tube. I am having difficulting figuring out how to cold crash my beer. For ales I don't worry about cold crashing in the fermenter; I just rack at fermenting temp to the keg and crash it there. But for lagers it is different (from what I've read). Diacetyl rest or not, lowering the temp causes a vacuum in the fermenter and would result in suck back from my blow off tube bucket. If I remove the blow off tube and seal up the fermenter the vacuum will still occur when I open the fermenter to rack to a keg, allowing a rush of oxygen into the fermenter. An airlock would just mean that Star San or vodka gets sucked into the fermenter and eventually oxygen once the airlock is sucked dry. How is this done? I'm I too worried about the oxygen? I could put a sanitary filter at the end of the blow off tube and let oxygen get into the fermenter, but at least it would be clean, right? I have searched quite a bit and haven't found a good answer. I've seen the C02 bag kit that captures C02 during fermentation and allows that C02 back into the fermenter, but it seems clunky.

[indianajns]

I deal with this problem by hooking my co2 tank up to the blowoff tube during cold crash. 2-3 times a day I pump a bit of co2 into the fermenter to equalize and eliminate the vacuum. Probably much better ways of dealing with this but this low-tech solution has worked well for me.

[CurtisG]

I've run into the same problem as you and I don't think you're worried too much about oxidation.

I've started fermenting under pressure so that when I cold crash it just drops the PSI a bit.

The bag method is a bit janky but I think it's a great way to combat cold crash aeration without modifying your fermenter too much. I was thinking of doing the same before I started fermenting under pressure.

[ScottK]

Thanks gents. Curtis/Greg, can you think of a way to hook up C02 to the Sanke fermenter kit? I made an adapter from the C02 tank to connect to the blow off tube with a barbed fitting to push the beer out. I wonder if this same setup might work? Would I set the regulator to a minimum, like 1-2 psi? I'd have to make sure the connection was sound as well. Greg, what does your connection look like?

[indianajns]

I just turn the tank on a crack, add a small amount of gas, and then turn off the tank. Between gas additions there will be a slight vacuum between the fermenter and the tank that will resolve itself when you add the gas. You should be able to connect it to the blow off? It doesn’t take much gas and a hose clamp on both ends should keep it air tight. Here’s a pic of how I have it. https://imgur.com/gallery/DQAZT3N You coming to riip on Thursday? EDIT: I used to have that sanke kit and just hooked up the gas to the blow off.

[ScottK]

Cool, thanks Greg. I'm sure I'll be able to make it work. Can't make it on Thursday. Cub Scouts den meeting

[CurtisG]

Cool, thanks Greg. I'm sure I'll be able to make it work. Can't make it on Thursday. Cub Scouts den meeting

Just make sure you have your racking cane closed when you ! unless you want to cold crash on the bottom of your fridge lol

[ScottK]

I've noticed that the compression connection is not airtight around the racking cane. Should it be? I was thinking about putting a valve at the end of the racking cane but it wouldn't make sense to do so if the compression connection wasn't sealed.

[bwarbiany]

I personally haven't worried about it. Usually what I've done is to loosen the tri-clamp fitting on the top of the sanke when I cold crash. I know it pulls in a little O2, but not a lot, and there's a nice blanket of CO2 sitting there.

I don't think setting your regulator to 1-2 psi is a good idea. It might start pushing beer out of your racking cane, which obviously isn't a good thing in your fermenting fridge... I think what is being suggested where you just crack the CO2 tank occasionally at low psi is not a bad thought.

As for connecting to the CO2 tank, I have an MFL fitting that is clamped into my blowoff tube. With that, I can hook up my CO2 tank when it comes time to transfer, and I transfer under pressure rather than using siphon.