Blow off v air lock

[marc777]

New Brewer here. My beer is on day 8 in the fermenter and the bubbles are now one every 2 minutes through the blow off tube. Is it "harder" for CO2 to get through and exit the blow off tube at this stage of fermentation versus through an air lock?

Thanks for this great site.

 

[Hamaki]

Because liquid depth over the end of your blow off tube is bound to be deeper than liquid depth in an air lock, yes. But it is a very minor difference and should not affect how long signs of active fermentation, like bubbling, continue. Still bubbling a bit after 8 days is within the normal range. Sounds like you're in pretty good shape.

 

[marc777]

Will the CO2 exit easier through an air lock and is that a better procedure? I guess I don't understand what effect, if any, the gas has on the wort in the fermenter, i. e., is it better to get rid of it in the most efficient manner. Thanks again.

 

[Yooper]

Will the CO2 exit easier through an air lock and is that a better procedure? I guess I don't understand what effect, if any, the gas has on the wort in the fermenter, i. e., is it better to get rid of it in the most efficient manner. Thanks again.

Co2 will exit either way. A blow off tube is just a bigger version of the airlock.

It really doesn't matter a bit which you use.

 

[CUrchin]

Essentially every time a bubble exits either the blow off tube or airlock, it is equalizing the pressure inside the fermenter with the ambient air outside the fermenter. There really is no difference, save the ever so slight pressure that is required to push the CO2 thru the liquid.

 

[Hamaki]

If you have relatively small head space in your fermenter and an active fermentation an air lock could clog & pop out, creating a mess and run a slight risk of infection. A blow off is much less likely to clog.

I use 3/8"tubing for a blow off and generally leave it in place throughout fermentation. I had one event well after active fermentation & CO2 production were done in which a temperature drop resulted in suck back of some nasty looking starsan & krausen and infected that batch. (Someone plugged the fridge into a regular outlet rather than the temp controller outlet) I don't believe that would have happened with an air lock if not overfilled.

I believe some make it a habit to switch from blow off tube to airlock after the danger of blow off has passed. There are also some that ferment under pressure generated by the CO2 produced and controlled by a spunding valve.

 

[marc777]

Thanks again. The info available from the veterans here is terrific.

 

[marc1]

I use fermcap to keep down the foam from vigorous fermentation. During the first couple of days of the ferment I leave my 3 piece airlock empty (only use the main one piece ) and cover it with sanitized aluminum foil. when fermentation slows a little I put the rest of the airlock together with starsan as the liquid. The airlock then works as intended without the need for dealing with blow off tubes.

 

[DurtyChemist]

CO2 doesn't care if it's a tube or an air lock. It's just the yeast slowing down. You could probably bottle it if the final Gravity is stable.