[mcdform]

I understand airlock suck back when crash cooling a beer but there's something happening that is weird to me.

I have four batches fermenting in one gallon wine jugs with airlocks.  The fermentation of each is complete and the temperatures of all four are the same but one of them is sucks the sanitizer back in daily.  Are there other reasons for the suck back? 

Three of the beers are session IPAs and the 4th (with the problem) is a big Wee Heavy.  Any help is welcome as I think a similar thing ruined my small batch of Foreign Export Stout. 

[Stevie]

Is there a crack in the airlock causing the sanitizer to leak? If at a constant temp, the vacuum inside shouldn't be enough to suck anything back in.

[morticaixavier]

+1 to steve's comment.

Also, get the S type airlocks and say good bye to suckback.

[HoosierBrew]

+1 to steve's comment.

Also, get the S type airlocks and say good bye to suckback.

+2.  That'll do it.  S-locks for me.

[Stevie]

+1 to steve's comment.

Also, get the S type airlocks and say good bye to suckback.

And hello to oxidation.

[mcdform]

Checked the airlock up, down and all around and found no signs of a crack.  I switched it out as a precaution just see what happens.  I'll update again later.

Do the S-Types really cause oxidation?  I'm brewing small batches so long term oxidation isn't really a problem since most batches are gone pretty quick.

[Stevie]

Do the S-Types really cause oxidation?  I'm brewing small batches so long term oxidation isn't really a problem since most batches are gone pretty quick.

The s-locks allow air to flow both ways. If some air gets pulled back in, it could. Personally, I prefer a 3 piece then use a solid stopper when crashing and moving.

[morticaixavier]

Do the S-Types really cause oxidation?  I'm brewing small batches so long term oxidation isn't really a problem since most batches are gone pretty quick.

The s-locks allow air to flow both ways. If some air gets pulled back in, it could. Personally, I prefer a 3 piece then use a solid stopper when crashing and moving.

right but every time you switch from the airlock to the solid stopper you let the same air in the S bubbler would have. if there is negative pressure inside the fermenter it will be relieved and air will be introduced. in a small batch situation it's even less of an issue.

[HoosierBrew]

Do the S-Types really cause oxidation?  I'm brewing small batches so long term oxidation isn't really a problem since most batches are gone pretty quick.

The s-locks allow air to flow both ways. If some air gets pulled back in, it could. Personally, I prefer a 3 piece then use a solid stopper when crashing and moving.

right but every time you switch from the airlock to the solid stopper you let the same air in the S bubbler would have. if there is negative pressure inside the fermenter it will be relieved and air will be introduced. in a small batch situation it's even less of an issue.

 +1.  I've used an S lock for some, stopper for others, and never noticed a difference in beer quality. The pressure is gonna equalize one way or another, at some point. I always assumed the blanket of CO2 from fermentation (being heavier) protected the beer.

[tschmidlin]

Do the S-Types really cause oxidation?  I'm brewing small batches so long term oxidation isn't really a problem since most batches are gone pretty quick.

The s-locks allow air to flow both ways. If some air gets pulled back in, it could. Personally, I prefer a 3 piece then use a solid stopper when crashing and moving.

I do the same, but it's not like a 3-piece won't prevent air from flowing back in.  It will suck in the liquid first, but air follows.  I use breathable bungs, which still suck in air when you relieve the pressure like Jonathan says, but absent opening it in a space flush with CO2 there's really not much you can do.  On the other hand, it is not just O2 but exposure time.  When I crack a carboy and rack it to a CO2 flushed keg, I don't worry about O2 carry over.  I'm pulling from the bottom, filling from the bottom, and there isn't much mixing.  I wouldn't stress about it anyway, just be aware of what you are doing in case you decide to change things up.