Only brew 2 gallon. Thinking of the 3g Fastferment, but see that people are posting/complaining about not getting an airtight seal on the lid. Some are building up with silicone and aftermarket washers. Question is, is this an actual problem? The Mr Beer kegs that I have been using up to now, have 4 notches in the threads so gas can escape. No airlock. An airtight seal is NEVER possible. Made some great beer in them, but one "melted" cos wort was too hot, another the lid thread cracked.