Originally Posted by TheBeerist
Just wanted to tell you not to worry about contamination. The CO2 sitting on top of your beer is providing a natural barrier against contaminants. Fear not!
Unless bugs can literally crawl or fly into your beer you should be fine. As Beerist stated, the CO2 blanket will protect against air and therefore airborne contaminants, but if ants or gnats can crawl or fly into your container, you may have issues. Just an FYI.