Airlock question

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Jbsmith18

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Let me start by promising this is not a "the airlock is not bubbling" question...

I just finished up my 6th batch. After cooling, aerating, and pitching my rehydrated yeast, I move my fermentor into my back room and apply the airlock.

On every batch this far,I come back to the fermentor approx 30 min later to see that the airlock has drained the water into the fermentor and the airlock cap is no longer floating, rather it is resting on the top of the tube with very little water left in the airlock.

I unattached the airlock, refill with water, reattach ... and it is normally works fine the 2nd time ( or for sure works fine on the 3rd attempt). What am I doing wrong? I have never heard anyone else discuss this topic.

Thanks,
 

Gavin C

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The beer is cooling more in the fermentor (FV) as is the air in the head space. it contracts and the reduced pressure inside causes the fluid in the airlock to be pushed inside by the greater atmospheric pressure outside the FV.

I don't put an airlock on till after the beer is at pitching temp and I've pitched the yeast for this very reason.
 

Qhrumphf

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Like he said, it's because you're sealing it up too warm, and as it continues to cool, the volume of wort shrinks (basic physics there), and as a result pulls a vacuum sucking the airlock fluid back in. It's also a common occurrence when staging a lager down to near freezing.

In this case, chill further, ideally down to a couple degrees below where you intend to ferment at.

Also, vodka or sanitizer in the airlock. Either way it's food grade and will prevent contamination in the case of suckback.
 

Subdivisions

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I noticed you talk about your airlock cap not floating anymore. Why was it floating to begin with? Are you using a bucket or a carboy? I've noticed in a bucket if your push on the lid and push air out of the airlock it creates a vacuum and quickly sucks some water back in. Maybe try letting the fermenter sit for a minute before putting the airlock on after moving it.
 
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Jbsmith18

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Thanks for the quick responses. It sounds so obvious after I think about it...

Subdivisions, I am using a glass Carboy if that helps. Wart was about 74F when I transferred.
 

Subdivisions

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Thanks for the quick responses. It sounds so obvious after I think about it...

Subdivisions, I am using a glass Carboy if that helps. Wart was about 74F when I transferred.

Ok, the warping of the fermenter isn't causing it. Maybe keep the airlock off until you move it. Wort sloshing around could absorb some air and cause a slight vacuum. With the good seal on the glass carboy it could be enough to suck the water in.
 

cooper

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A lot of people will put a piece of sanitized aluminum foil over the carboy mouth while the wort is chilling down to pitching temps and then let it sit like that for the first couple of days till the active fermentation is over or the need for a big blow-off tube is over. I also like to use an S-shaped air lock when im cold crashing as it will bubble both ways and it prevents the water/vodka from getting sucked in. But as blizzard said, it's not ideal for a vigorous initial fermentation.
 

lolcats

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A lot of people will put a piece of sanitized aluminum foil over the carboy mouth while the wort is chilling down to pitching temps and then let it sit like that for the first couple of days till the active fermentation is over or the need for a big blow-off tube is over. I also like to use an S-shaped air lock when im cold crashing as it will bubble both ways and it prevents the water/vodka from getting sucked in. But as blizzard said, it's not ideal for a vigorous initial fermentation.
Same here,

Foil for the first 3 days (or blow off if needed) than back to regular airlock
 

cooper

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It really help eliminate a lot of blowoff/airlock issues in those first three days. And if you have a dedicated fermentation chamber there is going to be so much C02 in the atmosphere that a person really doesnt have to worry too much about any other oxygen-loving bugs getting in there. I know I about knock myself out with a C02 burst to the face every time I open my ferm chamber (small chest freezer with the lid on top)
 

unionrdr

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This is why I chill the hot wort down to 75F or so initially. Then top off to recipe volume with spring water that's chilled a day or two in the fridge before brew day, This gets the wort down to 65F or so rapidly. It can get a decent cold break as well. But no suck-back from further cooling occurs.
 

joshesmusica

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When I'm moving around my fermenters (I have both buckets and plastic carboys), I take the airlock out. Pressure in any direction will cause suck-back or push-out. Neither one is desired.

I'm guessing you're not talking about an s-shaped airlock as the cap is never floating. Either way, it seems that your suck-back problem is due to cooling wort.

I use starsan in my s-shaped airlocks, and have noticed that during the vigorous part of fermentation it bubbles/evaporates very quickly. I pretty much have to fill it back up once a day during that part.
 

Ungoliant

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Every single one of my first 6 batches had some really aggressive fermentation. I had a bucket blow up in my closet (airlock popped, hops and wort all the way up the wall), lost a #2 plug in the bucket trying to attach a blow-off, and I had no other plugs that fit...Had to run across town to my LHBS store to find out they only had gaskets, come back to a huge mess...Gasket doesn't fit...Made an improvised plug by cutting up and drilling a Pink Pearl eraser. Ever since then, I only do a blow-off initially.

Silly question for you all. Why is it that a few of you are only chilling to 72-75? What's your chilling process?
 

Scriv

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I noticed you talk about your airlock cap not floating anymore. Why was it floating to begin with? Are you using a bucket or a carboy? I've noticed in a bucket if your push on the lid and push air out of the airlock it creates a vacuum and quickly sucks some water back in. Maybe try letting the fermenter sit for a minute before putting the airlock on after moving it.
He's probably using a 3 piece airlock like this, not an "s" type. In a 3 piece there's a floating top.

https://www.morebeer.com/products/airlock-3-piece.html?site_id=5
 

unionrdr

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Every single one of my first 6 batches had some really aggressive fermentation. I had a bucket blow up in my closet (airlock popped, hops and wort all the way up the wall), lost a #2 plug in the bucket trying to attach a blow-off, and I had no other plugs that fit...Had to run across town to my LHBS store to find out they only had gaskets, come back to a huge mess...Gasket doesn't fit...Made an improvised plug by cutting up and drilling a Pink Pearl eraser. Ever since then, I only do a blow-off initially.

Silly question for you all. Why is it that a few of you are only chilling to 72-75? What's your chilling process?
I chill down to 75F or so in a ice bath. The strain into fermenter & top off with spring water chilled in the fridge a day or two before brew day. This is cold enough to get the 75F wort down to 65F or so rapidly. Also gives a little cold break as a result.
 

Subdivisions

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He's probably using a 3 piece airlock like this, not an "s" type. In a 3 piece there's a floating top.

https://www.morebeer.com/products/airlock-3-piece.html?site_id=5
Ya, that's what I figured but I wouldn't expect it to be pushing up from CO2 pressure after only 30 minutes. Mine sits on the post until fermentation gets going well enough to produce pressure.

EDIT: Saw the OPs post about cooling down more. That could explain the bobber floating and the suck back when cooling down.
 
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