Fermenter head space and airlock hole

Question

Hi folks I'm after a bit of advice as its my first time doing home brew

1. I'm using Wilkos dark velvet stout. As it states on the tin to make 40 pints fill, to 23 litres. Now I have a 23 litre fermenting bucket, which gives me 2.5 feet space for the head. Is this enough space?

2. In the lid I have cut a hole for my airlock, and between the rubber that squeezes in the hole for the airlock to sit in it has a couple of small gaps. Does this matter? Does it need to be airtight, or is it better to have the extra gap?

Answer 1

1. The fermenter should not be full to the brim, there will be at least a couple cm of foam (kreusen) on top of the beer when the yeast get going. Without space, it will try, and succeed, to get out.
2. There should be no gaps in the fermenter. In theory, small gap wouldn't be so bad during the primary fermentation because the kreusen and the flow of CO2 will keep oxygen out, but:
   
   • a. fruit flies love beer too (and carry beer-spoiling bacteria).
   • b. after the foam goes away oxygen from the gap will ruin your beer.

Answer 2

1. The extra head space is fine. You need some space for the krausen which will build up on top of your beer. If it didn't have space to build up, it would eventually stop up your airlock and could either blow out the airlock or pop the lid off your fermenter. Here is more info on the krausen.

   A head of foamy krausen will form on top of the beer. The foam consists of yeast and wort proteins and is a light creamy color, with islands of green-brown gunk that collect and tend to adhere to the sides of the fermentor. The gunk is composed of extraneous wort protein, hop resins, and dead yeast. howtobrew.com

2. You do not want a gap. The reason for the airlock is to keep air (oxygen) and other living organisms such as bugs and anything that could infect the beer out. Do you have something you can fill the gaps with?