How to Fill a Keg With Nitrogen

There's an easy way to fill up a keg without worrying about bubbles or foam. Oxygen can make its way through the foam, right? And sometimes it gets bound up by the foam, but sometimes it also makes it into the beer. We say foam on beer because it's CO2 that's pushing out of solution. But like you said with star sand foam, I'm pretty sure that's mostly air. The next question comes from Duke Oster says low gravity beers have crummy head.