Concerned about CO2 buildup in cooler

Heya all, I've made it a whole two batches without freaking out and asking questions (RDWHAHB!) but I'm finally at my limit and would like to get some opinions on my current issue

I've built a cooler for my fermenting bucket by using two plastic containers. One container sits normally on the ground, with the fermenting bucket inside, and the other sits upside-down on top of it. They form a sort of clamshell around the bucket, creating a relatively airtight space to put ice in. I then wrap blankets around the containers for insulation, and add a few weights on top to keep the seal tight.

My concern is that the CO2 has nowhere to go. When I remove the top container to change out ice, the smell of the brew is really strong. I worry that the escaping gases will have nowhere to go, and eventually might have trouble leaving the bucket. I guess this is how carbonation works?

I realize my two plastic containers are not perfectly air tight, and the plastic likely leaks some air naturally, but I really don't want to be in a situation where the CO2 leaving the fermenter is having more difficulty than normal leaving. On the other hand, venting the gas somehow will leak the cool air I'm trying to keep inside.

I suppose what I'm asking is whether or not the CO2 issue is a valid concern, and if I need some type of vent. Many thanks for the help!

I'd guess that when there is too much co2 in there, the top bucket will blow off of the bottom one.

I built a new lid for an igloo cooler, so that the airlock pokes through. I'll post a picture here in a minute.

Edit: like this:

Nice! I hadn't thought to extend the airlock outside the container somehow. I'll work on doing this.

Also, to refine my question a little more, would having excessive built up CO2 slow down the yeasties in any way? I guess that is the root of my concern, that the yeast will be forced to work harder when a ton of CO2 is present and possibly even stall fermenting. Is there any truth to this or am I doing the classic "worry my newbie *** off" routine?

I have been fermenting inside an air tight chest freezer. Sometime I have two batches going at once. The gas does build up substantially so that you definitely don't want your nose any where near the inside of the cabinet.

With the pressure differential between the fermenter and the cabinet there shouldn't be any risk of a vapor lock but at worst case I think you'd have a scenario similar to a blocked bubbler on a bucket. That is, eventually the gas pressure will win either by blowing the lid off or by cracking the styrofoam.

Right- I don't think you have to worry about the yeast not working. Yeasts ferment nicely in an anaeorbic environment. You might have to worry about the plastic cracking or exploding, due to the pressure of the co2. It should be vented so the pressure doesn't build up.

Don't worry about the beer or yeast, people ferment under pressure all the time (and end up with already carbonated beer) and claim that it is even better than the usual airlock fermentation.

The only worry is if you make a completely airtight container you would "explode" it but probably not even to any cool extent.

I have a chest freezer and I imagine that it just cracks the lid a bit as it builds up a tiny bit of pressure.

sinoth said:

Nice! I hadn't thought to extend the airlock outside the container somehow. I'll work on doing this.

Also, to refine my question a little more, would having excessive built up CO2 slow down the yeasties in any way? I guess that is the root of my concern, that the yeast will be forced to work harder when a ton of CO2 is present and possibly even stall fermenting. Is there any truth to this or am I doing the classic "worry my newbie *** off" routine?

Click to expand...

Heck, don't try to extend it, just buy a seperate airlock for the lid