How tightly does a fermentation bucket need to seal anyway?

[Bennypapa]

Over last weekend I brewed a Founders Kentucky Breakfast Stout Clone.

13.25 lbs 2 row
1.5 lbs flaked oats
.75 lb chocolate malt
.75 lb roasted barley
.5 lb carafa III
.5 lb c120l
mash 155 for 60minutes, sparge til pre boil gravity of 1.055 (this is lower than the recipe but where I wanted it.
boil 90 minutes
1oz magnum @ 60
1.25oz willamette @ 25min
2.5 oz bittersweet chocolate@ 15min
1.5 oz cocao nibs @ 15min
1.75oz willamette @ 10 min
2oz sumatran coffee @ flameout

OG=1.072 (again lower than recipe but what I wanted)

wlp-001 yeast 2 stage starter made on stir plate chilled and decanted each stage

Fermenting in a bucket with a blowoff tube in a 62-64 degree basement. I started in the 64 degree area of my basement. 48 hours in the fermentation had picked up to a good pace. The thermometer sticker was showing 68-70 degrees so I moved to a cooler 62 degree part of the basement.

I must have sloshed the wort onto the lid because to my alarm I heard a bit of hissing around the bucket rim as co2 escaped through the wort that had sloshed into the lid/bucket joint.
Now, I've always assumed a fermenter should be sealed air tight so as to avoid oxidation. This one obviously doesn't and that puzzles me because I've never had a batch come out oxidised.

So, How tightly does a bucket fermenter need to seal?
While fermentation was strong I wasn't too worried because pressure inside the container was higher than the air outside the bucket but now that fermentation has slowed I was thinking of moving everything (beer&yeast) to a corny keg with an airlock for a more airtight container. Is this a good idea?
Should I move the yeast cake with it or would that depend on the level and stability of the gravity?
Does anyone have any good ideas for testing how tightly a lid/bucket pair seals? I have a couple of buckets and lids and I'd like to test them out to find the best sealing pairs before my next brew.

Thanks all, Cheers.

Ben

 

[geckholm]

You're fine. The CO2 escaping is preventing O2 from entering and the lid is still stopping stuff from falling in.

 

[BlkWater_brewer]

Normally the bucket should be air tight to a point, however some are more so than others. The hissing you mention shouldn't be an issue. The sloshing usually unleashes excess CO2 . The fact that you heard hissing would indicate the leak was under pressure and not a wide open seam. I wouldn't worry about it too much. During fermentation there will always be a higher pressure in your bucket even when the bubbles slow near the end. Bucket lids can wear quickly and I do change mine fairly often. This is one draw back that glass doesn't have. To see how bad the seal is, simply seal the airlock hole put some water in, make sure the bucket rim and lid are dry then flip it over. If it leaks then there could be an issue, depends on how big the leak is.

If you are that concerned, simply seal around the lid with duct tape. A corny keg would most likely leak even worse as pressure acts to seal them anyway. Don't perform an extra transfer, it would do more harm than any oxygen that may have leaked in.

 

[Ozarks Mountain Brewery]

until there is no positive pressure coming out, the only reason to have a lid on is to keep unwanted pest out and of coarse look at the bubbles but none at all for fermentation, for thousands of years they didn't even use lids for best results while its blowing hard or hissing, take it off for a day or 2, when foam comes through the blow off tube your losing yeast you need

 

[unionrdr]

I had a Brewer's Best ale pail that had no lid seal that did that under pressure. It finally got infected, so I tossed it for the shorter Midwest 7.9 gallon bucket with lid seal. The BB one always leaked around the lid during initial fermentation.

 

[DaNewf]

You can buy fermenters that do not seal at all probably the most famous being the Mr. Beer keg. The threaded section that accepts the lid is intentionally slotted to allow CO2 to escape.

The Cooper's DIY fermenter (and now the smaller Craft brew fermenter) use a lid that just lays on the bucket. CO2 production causes the lid to lift just enough to vent and equalize the pressure. I've been using mine for three years now.

Many large primary fermenters made for wine making use a lid that snaps on very loosely.

Finally a lot of brewer's just put cling wrap over the bucket and secure it with some kind of elastic, sometimes the o-ring out of the bucket's lid (the same o-ring that was supposed to make the bucket air tight).

 

[Bennypapa]

I had another thought. I was mainly worried about air getting in after the initial active fermentation was over but c02 is heavier than air so unless the layer of co2 is disturbed air should not be able to get in the bucket.

The thing you think of when trying to fall asleep huh?

 

[unionrdr]

Well, in the event of a suck-back, the Co2 absorbs the O2 to a certain point. One doesn't sit on top of the other. But this is where the arguments start with chemistry students & the like...