How To Use A Blow Off Effectively


What is a blow off hose?

Normally this is used for carboys.  Essentially it is a hose that you put onto the air lock or to replace the air lock.  No matter what, a hose is attached and then goes into a large container of water.  In essence you have created a very large air lock.  In the example listed below, they just attached the hose to a 3 piece air lock.

Why is it used?

The shape of the carboy makes it so that during fermentation, the head will rise up and get funneled towards the top of the carboy.   If fermentation is strong enough, head from the beer will rise into the air lock.  Sometimes it can clog the bottom of the air lock so no gas can escape.  After enough pressure has built up it will blow the stopper and the air lock right out of the carboy making a huge mess.  This can be seen with some stouts, or wheats.


Where people have gone wrong…

This mistake can not happen if you are attaching the hose to the air lock but rather putting in larger hose into the actual neck of the carboy.  What you want to make sure you avoid is, to stick the blow off tube to far into the carboy and beyond the neck.  What will happen is that when the beer rises it will create a suction and you will start to siphon out your beer into your water container.  So make sure that if you are putting a blow off into the neck of your carboy you are conscious about how far it is actually in there.  Otherwise you will lose a lot of beer.

Note for those that want to do a blow off…

Know that you don’t have to take your blow off tube off ever.  Just make sure it is submerged into a container of water and life will be good.  Some people switch it out but I never do.

If you have a glass carboy and want one that is going to fit into the neck of your carboy you need a a 1 inch diameter hose, if you want a hose to fit into the stopper hole or grommet you need a 5/16 hose, if want a blow off to fit over the middle part of a 3 piece air lock you need a 7/16th hose.  

Hope this helps.



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