I'm getting ready to fire up my next 5gal batch with my new MiniBrew conical and realize the plastic top on this thing is just a flimsy piece of rubber that seems like it wouldn't be ideal for a closed fermentation. Anyone have any experience with one of these? Chiefly, is it ok to ferment with just that rubber piece on the opening or do I need to rig up a way to clamp it to keep it in place and keep the nasties out?
