Blow hose, Airlock, and Fill Volumes

Two quick questions from a newbie:

I have heard two conflicting versions of what to use during the primary fermantation: One claims that no matter what volume carboy (5 or 6 gallon ) that a blowoff hose should be used. The other claims that if one is using a 6 or 6.5 carboy no blowoff hose is necessary only an airlock. What are your thoughts?

My second question is regarding the fill volume when using a blowoff hose. I just watched a DVD (How to make a Better Beer) that suggest topping your initial fermantation volume to 5.5 gallons instead of 5 gallons. They claim one will lose a half gallon or so during primary fermentation and racking. Is this a good practice?

Thanks much guys,

Jim

JWJ, I'm not experienced either, but one of my books says that using a blow off tube gets rid of some bad flavours in the beer.

That said, I'm brewing in the Beer Machine, which is a totally sealed unit, and the beer tastes great... Possibly the mixes for the machine are designed differently? More likely it just doesn't matter one way or the other, would be my guess. But it really is a guess.

If you're using a 6 or 6.5 gallon carboy, you don't need a blowoff tube. I usually use one just in case the yeast goes completely ape-@!#*. After a couple days, I switch to the airlock. I think the blowoff tube only gets rid of bad flavors if foam and krausen actually get blown out. Otherwise, it's just like using an airlock.

The suggestion of topping off to 5.5 gallons is fine, you will definitely lose some volume during the process. I usually don't top off. So I usually have slightly smaller batch sizes, roughly 4.5 gallons per batch, but the beer is a little stronger, and I like that.

I've never used a blowoff tube before as I ferment in a 6.5 gallon carboy, so I can't comment on that. As for topping off to 5.5 gallons....I would think this would dilute the beer somewhat unless the recipe was created to make a finished volume of 5.5 gallons. If the recipe is formulated to produce 5 gallons, then adding an additional .5 gallon of water to the fermenter will just serve to lower the gravity.

when i stuff six gallons of beer in the 6.5 gallon carboy i have to use a blow off tube everytime. when i only stuff 5 or 5.5 gallons in there, the airlock seems to be sufficient.

vtfan99 said:

I've never used a blowoff tube before as I ferment in a 6.5 gallon carboy, so I can't comment on that. As for topping off to 5.5 gallons....I would think this would dilute the beer somewhat unless the recipe was created to make a finished volume of 5.5 gallons. If the recipe is formulated to produce 5 gallons, then adding an additional .5 gallon of water to the fermenter will just serve to lower the gravity.

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Not necessarily. When you factor in the volume in the fermentation vessel that is taken up by trub - the settled solids and fallen yeast - then you have to top up past the five gallon mark on your vessel to actually get the five gallons you were brewing to get. I just about always throw in at least an extra half-gallon to account for that.

bikebryan said:

Not necessarily. When you factor in the volume in the fermentation vessel that is taken up by trub - the settled solids and fallen yeast - then you have to top up past the five gallon mark on your vessel to actually get the five gallons you were brewing to get. I just about always throw in at least an extra half-gallon to account for that.

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Keep an eye on it if you think you need a blow off then put one on before you fill your airlock with brew??????????????

The valve you use will depend on the beer you make and how much beer you have in your container. Typically, i use either a three piece air lock, or a bubbler on my fermenters (6.5 gallon buckets) and usually, they have about 5 to 5.5 gallons of beer in em. works fine. However, the last beer i did, another strawberry ale, not only is very sugary, but it was maybe 2 inches down from the top in the fermenter, so i used a blow off style air lock. (basically a tube running into a bucket of bleach water.) and its a good thing i did, because, as i suspected, i got a decent amount of liquid blowoff during the first few days of fermentation.