Here is my scenario. I set out to brew 10 gallons of a low gravity Belgian ale dubbed patersbier. I kegged 5 of it after a month and started drinking what turned out to be a very tart almost sour version of what I had brewed. Disappointing. A couple weeks later, a film with bubbles formed over the remaining 5 gal. in the secondary. I was using the Trappist from wyeast so... Anyway I've racked back into a 6.5 gallon carboy and added blackberry purée to change it up and go with the flow. I'm going to age it like a lambic. What I'm most worried about is oxidization and having my beer turn to vinegar. Any advice? Should I rack back into a smaller vessel to cut down headspace? With the pellicle gone, should I maybe induce some co2 periodically? Thanks for any help!