So I just received my first Speidel variable volume stainless steel tank and I have a question about the two-piece, screw-together airlock that comes with it. It appears that, when screwed together tightly, it will completely seal the unit, preventing air from entering and CO2 from leaving. If I screw it together only loosely, it would seem to allow gasses to exchange from both directions. In other words, it's either sealed or it isn't. There doesn't seem to be any way to allow CO2 to escape without the possibility of air entering, like traditional water filled airlocks do. Is that correct or am I missing something? And is this a problem? I know during active fermentation there will be positive pressure inside and a layer of CO2 over the wine, which should pretty much prevent air from contacting it. But when fermentation slows down, I'm a bit concerned that if the airlock is unscrewed a little, it might allow some air in.