Improvised cold crash CO2 suck-back reservoir

[Horseflesh]

I have always let the fermenter suck in air when cold crashing, which may not be great for hop quality. Today decided to see if I had anything I could use to hold a volume of CO2 to feed the fermenter as it chills. Being out of party balloons, I came up with this monstrosity:

That is a produce bag, a drilled stopper, and a coffee stirrer jammed in to my blowoff tube. The bag is fed through the stopper and then down around the outside before plugging it into the tube. (The coffee stirrer prevents the plastic bag from plugging up the hole in the stopper, so gas can move freely.)

I inflated the bag with a scrap of the same hose and a carbonation cap, then switched it to the sanitizer end of my blowoff tube.

I don't know how much this can really help, that plastic bag is probably highly permeable to oxygen, and the seal at the plug is probably not air-tight... but the working pressures are low and it can't hurt to try it.

So what kind of plastic bag is cheap, tough, flexible, food-safe, and impermeable to oxygen over the course of a few days? It should be possible to make something less hideous and more easily inflated and re-used.

 

[Redtab78]

This is what I use (ignore the CO2 comming into the top of the fermentor and the transfer, this is just to show the CO2 suck back thing). Before I bought the fancy stainless lids and jars from Jaybird over at Norcal, I made my own using empty gatorade bottles and drilled stoppers. The idea is during fermentation, the CO2 pushes all the starsan from the first "tank" over to the second tank while filling with CO2, thus leaving a full 1/2gal mason jar full of CO2. Then when the cold crash suck back occurs, it will only suck back the CO2 from the first jar. at the same time, the sanitizer is being sucked back from the second jar. I think the entire set up cost me about $10 for the home made version, or you could hop over and pick up this exact setup from jaybird. It eases all my concerns for oxidation, and have yet to have a single issue.


And in case anyone happens to ask, the set up in this picture, is also simple, when I transfer, I run a CO2 line from my bottle into the secondary, and let it run for a little while essentialling filling the entire carboy with CO2. Then I "push" the beer out of the primary into the already CO2 filled secondary using CO2. the valve at the top is how I adjust the flow. If I turn the valve off, it will suck CO2 from the blow-off set up, so I bump the valve open until I am pushing the beer while also keeping the blow-off tank from sucking back. It may not be the "perfect" no oxygen setup, but I have had very good success using this method, and have yet to get a single oxidation issue.

 

[Horseflesh]

The double jar setup does look like the way to go, there’s no extra step needed when you begin chilling. I’ll have to make or buy one of those.

I also have the Brew Bucket and should do something similar for transfering under CO2.

 

[Redtab78]

The double jar setup does look like the way to go, there’s no extra step needed when you begin chilling. I’ll have to make or buy one of those.

I also have the Brew Bucket and should do something similar for transfering under CO2.

You are correct, you just simply lower the temperature on your controller and forget it

This is the one I got, but I dont use any ball lock attachments:

https://www.norcalbrewingsolutions.com/store/Ultimate-CO2-Canning-Jar-Harvesting-Kit.html

For the CO2 inlet at the top, I got that as a weldless kit from brew hardwar I believe it is just a 1/4" MFL bulkhead fitting, and for the CO2 tube a standard 1/4" ball valve. I set the pressure on the regulator down to about 2psi so that if I bump it fully open, it doesnt get to mush pressure.