Wort poured through the top in fermenter

[Sergiy]

Next day after i added an yeast to fermenter, i found that wort poured through the top, and polluted an airlock. Why it happend? I used US-05 yeast

 

[flars]

That is called blowing off. You may not have had enough head space in the fermentor for the krausen to form in. The fermentation could also have started too warm forming an overly large krausen filling the head space even if it would have been adequate for a normal krausen height.

Cover the mouth of the carboy with sanitized foil while you clean up the top of the carboy and clean out the air lock. Check the temperature of the fermenting beer. US-05 is best in the range of 66°F to 70°F. Putting the fermentor in a tub of 66°F water will slow the fermentation a little by absorbing some of the heat produced by the yeast if the fermentation is too hot.

The sanitized foil can remain on the carboy if the krausen is still rising.

 

[JohnSand]

Flars is exactly right. For a five gallon batch you want a 6.5 gallon container. You can also search "blow-off tube" on this forum, which is just what it sounds like. Don't worry, your beer will be okay, and we've all had this happen.

 

[flars]

I should have mentioned the blow off tube @JohnSand. This is what the blow off tube assembly looks like using the three piece air lock.

 

[beer4ever]

I just started using buckets as the glass carboys were too much for my back due to injury. What is about the right amount of headspace in inches from the brim? I’ve got a 7gal, a 5gal and a couple of 3.5gals. I plan to split batches into my 3.5’s if possible to reduce the load on my back. Just approx. Thanks.

 

[flars]

The recommendation for most ale yeasts is 25% of the volume of the beer for head space. Highly active yeasts like WY 3068 need at least 33% of the beers volume for head space. I don't have buckets to measure the inches.

 

[JohnSand]

I think a normal 5 gallon batch, 5.5 into the fermenter, can be split into two 3.5gal buckets. Many standard fermenters are 6-6.5.
Sorry about your back, I've suffered in the past. I hope you recover well and soon.

 

[beer4ever]

I’m gonna go with 25% headspace. It pretty much lines up with the rib of the bucket near the top. Interestingly enough the lower rib figures to be about 30-35% volume. Huh? Thanks...