Any way to purge O2 from a plastic Big Mouth Bubbler before filling?

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Sep 4, 2011
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In the past year I've switched from primary/secondary to primary only, and started really trying to reduce my O2 exposure (closed transfer, fully purged kegs, etc.)

Right now I'm brewing a Pliny the Elder Double Dry-Hopped clone, which has two fairly large hops additions at day one and day six. I've read that it's best to just toss the pellet hops in, instead of bagging, so that's what I'm doing. Because of everything going on with this beer, I'm planning to use a secondary for this one.

I use a five-gallon Big Mouth Bubbler for my secondary. I've been trying to set up a way to purge it before I transfer to it. I've got a dual port lid for it, and I've set up two drilled stoppers to simulate gas and liquid dip tubes. I tried a test run today, but when I apply low pressure (1-2 psi), the lid literally blows out of the Bubbler before anything starts coming out of the liquid dip tube. Obviously these were not made to handle pressure, but I thought they'd be able to take a little.

I was wondering if anyone is doing something, or has any other ideas on how to purge one of these fermenters?

Thanks for your help!
Maybe purge the secondary fermenter with CO2, then get a siphon going in primary? Hang a CO2 supply hose in primary to maintain a blanket of CO2? I kind of did this kegging to keep O2 exposure down.
This is the first time I used active fermentation to purge anything. I needed to purge a keg too, so I did that first. I know the fermenter puts off a lot of bubbles, but I was amazed how fast it purged the keg. Five gallons out in a little over three hours.

Since that worked so well, I decided to try the Big Mouth Bubbler again. Same result; the lid pops out before it starts draining. I realized the main issue is that the silicone gasket on the lid gets slick when it's wet, and I sanitized everything when I assembled it. I've included a picture of my "solution". It won't win any awards for looks, but it's working so far. I just needed to put some weight on the lid to keep it down.

As I mentioned at the start, I rarely use a secondary any more, but this isn't a perfect solution for when I do. After this brew is done, I plan to look through my scrap lumber to see if I can build a small frame (2x4's probably) that the Bubbler can sit in. If I had something like that, I could put a small piece of wood across the lid and clamp it on each side. That would definitely hold it down and remove the risk of the 25 pound weight falling off. :rolleyes:

It's hard to tell in the pic, but I have my drain bucket sitting on my lift table. When I first started to purge my keg, I had the bucket on the ground and the sanitizer started rushing out. Once it started, it became a syphon, which is not what I wanted. I raised the bucket up so the hose was above what I was purging; now it only flows out as the CO2 flows in.

Big Mouth Bubbler Purge.jpg
That IS impressive! I've never done this method myself, quite surprised at your results!
Yeah, it's day two for a double IPA with a S.G. of 1.074, so very active fermentation, but it was still very surprising. I'm glad I was keeping a close eye on it as my buckets only hold around 2.5 gallons. This is in my basement, so it would not have been good if it started overflowing. Next time I'll probably go to a five-gallon pail for collection.

Definitely something I plan to continue. Very easy, for the keg purge anyway, and saves my CO2 tank.

If this is something anyone is thinking about, you do need to include a catch container between your fermenter and your purge line, in case you have any blow off. Here is my original post asking if anyone was using this method. A lot of good info, and some great pics of day_trippr's setup. I used an old Milk Bone plastic container we had on hand; very similar to the one he uses. My Post: Is anyone using fermentation CO2 to purge their kegs?