Volume loss using a blow off tube

I always split a batch of beer that is going to ferment rather violently. That way there is no beer and or yeast loss.
Otherwise try to use a 6.5 or bigger ferment or for a five gallon batch.

 

If you fill it too high, there's really no place for what is in there to go while it is in peak fermentation except for out. Your issue is you don't have enough head space for what you are making.

 

Fermcap is your friend

 

I use a bigmouth 6.5 gal for the majority of my clean beers. My batches are typically 5.5 gal batches so around a gallon of headspace. I've never lost beer using a blowoff tube though, and have never used fermcap before either. Did you use a lot of hops in your recipe? the hop trub will tend to soak up some beer in the end, leaving you with less.

 

I find it hard to believe that you lost 3 quarts of wort simply by using a blow-off tube. The only thing that 'blows off' should be (primarily) yeast and CO2 - unless you somehow had the tube shoved down into the wort instead of the headspace? Then I could see a significant loss of wort/beer as the building pressure in the headspace would force liquid through the tube and siphon action would talke over until the end of the tube was no longer submerged and the gas could vent directly. I have to think, though, that you'd notice something was wrong when a bunch of liquid started flowing through the tube!

All that said, how sure are you that you had 5 gallons to start? And how much was left in the bottom with the trub after racking?

 

@DunkelFester i have lost a half gallon fermenting an 1.100 Russian imperial with a blow off tube just stuck inside a 5 gallon fermenter. Big waste an lesson learned.

 

Yeah, there's a reason the ~ 30% headspace rule of thumb came to exist.

 

Concerning blow-off tubes, I have seen pictures of many homebrewers using a blow-off tube with the end inserted in some sort of container. The problem is that the container is sitting beside the fermenter, but at a level below the top level of the wort (often on the floor next to the fermenter). This is only asking for a large volume of wort to siphon off into the container. I always keep the container on a shelf or ledge ABOVE the level of the wort, as high as possible. Any wort trying to flow up the tube is brought back down by gravity, and it THEN becomes difficult losing any wort, except perhaps during extra strong fermentations (in which case I insert a 1-1/4" blow-off tube directly in the neck of the fermenter).

 

Theoretically that is possible to happen, especially if the blow-off liquid container is lower than the beer and quarter-inch tubing is used, so I'll suggest that it's better to use a 1" blow-off tube stuffed into the mouth of a 6.5 gallon carboy and avoid any possibility of this happening.

 

I agree, but even with a 1" siphon tube, for strong fermentations, it should be elevated above the level of the wort. I have had such violent fermentations (making a Belgian at a high temperature) that it too, would have siphoned down the larger diameter tube if the level of the end of the tube had been below the level of the wort. I raised the 1.25 inch siphon tube about 2 or 3 feet above the level of the wort, and even then the wort travelled up the tube quite a ways before falling back down.

 

Yeah, you're right. I was thinking that the physics of siphoning requires the full diameter of the tube to be filled with liquid before a siphon action can occur, meaning it's nearly impossible with a 1" diameter tube, but once that liquid gets over the high spot of the tubing, it's probably going to try to keep pulling beer behind it on the downhill side.

 

Right - it was more like a thick foam flowing up the tube, pulling other foam up behind it than solid liquid. The foam itself had a siphon-like effect.

 

Although your blow-off tube does rise some distance before falling back down to the container, I would still elevate the container above the level of the wort in the fermenter. The foam can actually rise up a long way, especially in the smaller diameter blow-off tubes. The yeast coming off through the krausen is often the healthiest yeast, but losing a little shouldn't make much difference. I think that the volume of beer lost through siphoning action would be of more concern.

 

I would not tape anything into place. If the blowoff tube clogs, you want something to give way before the fermenter body does.

 

The issue with putting the container above the carboy is that if the temperature drops, you could create a siphon from the starsan into the carboy. I'd rather lose a gallon of beer than 5 gallons.

edit: Actually I'd rather lose none. I use sanitized foil for the first few days of fermentation on higher gravity beers and then switch over to an airlock