Airlock Alternatives

Just use the bottle cap with a tiny pin hole

I prefer to have a crystal clear view of the activity in my fermenter, so I did away many years ago with my opaque fertiliser lids and airlocks. Instead, I use kitchen cling wrap, stretch it across the open fermenter neck, and secure it with a large and strong rubber band. CO2 escapes via a pin hole created with, you guessed it, a pin.

This has worked for me with no problems, and no airlocks to clean and sanitize.

I wanted to start making mustang (wild) grape wine in the cellar of the old house I owned during the 1980s-90s. I went to a liquor store that also sold winemaking equipment and looked at a couple of airlocks that would fit the 5-gallon water bottles I was going to use to make the wine. I took the locks to the counter and asked the owner, who was in his 60s at the time, if one was better than the other (they were a bit different but about the same price). Instead of trying to profit by selling me the locks, he was thoughtful and gave me some excellent advice. He said that he could sell me the locks for about 60 bucks apiece, but I'd be as well off for a LOT less money if I used condoms in lieu of the locks. He said he'd done it for many years (decades) and his wine always turned out great. He said that I needed to use condoms WITHOUT spermicide because that would kill the yeast. I thanked him heartily and went on my way. I couldn't find condoms without the spermicide ANYWHERE, so I bought some with and washed them thoroughly with soap and warm water. Starting with my first batch, my wine came out GREAT - and from that point on, I told folks that I do "safe winemaking." ;-)

Ginger beer fermenting in 6-liter water bottles with simple baggie airlock.

Personally, I have a jury-rigged blow-off. I have the typical universal Carboy bung that the airlock goes into, and put in my old racking cane (that was wanting a use once I bought the auto-siphon). Then attach the hose that fits the racking cane, bottling bucket, bottle filler, etc. and coil in a spare 1-gallon bucket with water. Might not be as good as a real blow-off hose, but it has worked on some surprisingly active fermentations.

I've also heard of using the balloon trick mentioned above, only that you drain the air a few (3-4) times per day.

Find a huge plastic bin with a top that you can put your fermenter in. Sanitize the walls of the bin. Put in the carboy of wort. Pitch a huge starter... and welcome to the world of open fermentation.

EDIT with addition:
I suppose you could just as well put an inverted glass cup over the top of a carboy. That would keep stuff from drifting in from above. I might have to try this sometime.

A sanitary piece of aluminum foil crimped over the top or even a plastic baggy with a rubber band on the outside (either use a new roll/box or pour some of your favorite high proof liquor on it just to be sure) should do the trick.

• Bacteria and wild yeast in the air typically move with air currents (cough/sneeze/fan/air vent...), but without any air current they will generally drift downward (its raining bacteria!). That being said, some crimped foil or baggy over the top will prevent any bacteria/wild yeast from falling into the fermentor (they won't drift 'up' as easily) while allowing CO2/fermentation junk to simply come out the bottom.

• here is a yeast starter as an example: http://www.manskirtbrewing.com/starter.shtml

This is a fun game.

How about a condom with a small hole poked in it? Lubricant free, of course.

There is definitely a slight chance of contamination, but a pin prick of a hole is better than open fermentation. And the condom should be a tight enough fit to make a seal around the neck of the carboy. Might need to buy Magnums though...

I have no idea if this would work, but if you were using a carboy couldn't you just stretch a balloon over the top and put a few small holes in it with a pin? I would think the hole would seal up, but open if there is enough pressure from the CO2 and allow the gas to escape without letting oxygen in. Obviously I have never tried this, but your question got me thinking and I think maybe this would work in a pinch.