I recently transferred about 4 1/2 gallons of beer from my bucket into my 6 gallon carboy. My concern is that with quite a bit of headspace it's at risk for infection because there isn't enough c02 being produced in the secondary to protect the beer from air... any thoughts?
No, if you've sanitized properly you shouldn't risk infection. Maybe oxidation might dull the flavor of your beer.
Fermenter 1 - Vienna /Saaz SMaSH
Fermenter 2 - Dry as a bone
Drinking - various craft brews, Tiny Bottom PA
Beer styles I'm trying to nail down: APA, Porter, Mild, Amber, & Something Yellow and Fizzy.