Can open fermentation be done simply by putting the fermenting beer in a bucket carboy and covering it with foil?
The purpose of the foil would be to just keep airborne contaminants from falling into the wort.
Despite being "covered" with foil I would think that any restriction on the head space would be negligible compared to an air lock. So I don't think it would be much different than having a bucket wide open.
I am considering this because I don't have an area that is clean enough to just let something sit open for a fermentation. Especially, if I want it to be in a temperature controlled environment like a fridge.