Too much water in airlock?

[BrewRI]

What are some problems that can arise from having too much/not enough water in an airlock? I imagine not having enough wouldn't keep the bacteria out and could risk an infection but what about having too much, 75-90% full instead of 50-60%.

 

[MikeG]

I'm guessing you're talking about the 3-piece air-lock where the free floating piece bobs up to let the gas escape. I've had mine overfilled, it was stuck on the cap but eventually the gas made it out.

I've read that some people only use aluminum foil instead of an airlock so that there is no pressure inside working against the yeast but I wouldn't worry about it.

 

[mattjmac]

You risk an infection from suck-back. Particularly if you are using a plastic fermentation bucket. When you move it/take the lid off of it you can create a negative pressure which will cause the bucket to suck the water back through the airlock and into your beer. Bacteria, etc. can grow in the airlock water and would now be in your beer. Use cheap vodka to avoid the bacteria growth and don't overfill. Just keep an eye on the airlock every couple days and top off with vodka to account for any evaporation.

 

[maida7]

You risk an infection from suck-back. Particularly if you are using a plastic fermentation bucket. When you move it/take the lid off of it you can create a negative pressure which will cause the bucket to suck the water back through the airlock and into your beer. Bacteria, etc. can grow in the airlock water and would now be in your beer. Use cheap vodka to avoid the bacteria growth and don't overfill. Just keep an eye on the airlock every couple days and top off with vodka to account for any evaporation.

I use star san in my airlocks to keep bacteria from growing. I use the better bottles and one of the major downsides is that they can suck in the airlock water when you pick them up.

 

[mattjmac]

I use star san in my airlocks to keep bacteria from growing. I use the better bottles and one of the major downsides is that they can suck in the airlock water when you pick them up.

That would be even cheaper than cheap vodka. Thanks for the idea! Can't believe I didn't think of this before.

 

[bonzombiekitty]

The problem with using starsan is that it foams. Last time I used starsan, it foamed so much that it overflowed the airlock and by the time I noticed it, there was only a tiny bit left.

 

[mc_eric]

I use starsan in my airlocks as well. You just need to make a habit of checking on it once or twice a day while the beer is in primary, and top it up as needed. The pressure can cause most of the starsan to foam out of the airlock.

 

[maida7]

The problem with using starsan is that it foams. Last time I used starsan, it foamed so much that it overflowed the airlock and by the time I noticed it, there was only a tiny bit left.

Initialy I always hook up a blow off tube to a bucket of star san. With the better bottle your limited to a 6 gallon fermenter and I almost always need the blow off tube. Once things slow down a bit I replace the blow off with a 3 piece airlock filled with star san. There is some foaming but it's not so crazy. If the foaming really bothers you, you could use iodaphor.

NOTE: both star san and iodaphor lose effectiveness over time. If you leave it there for weeks and weeks, you should probably replace the star san / iodphor every so often.

If your using a glass carboy your probably fine with regular water in the airlock.