I'm one week into a my addition of brett to a beer that I transferred out of a keg I wanted back into a secondary fermenter. The beer only filled 2/3 of the fermenter. I had intended to make some wort from extract to top off the fermenter to the neck, but one week has passed and there is about a quarter inch pellicle. Both the pellicle and topping off will help lower oxygen intrusion from the headspace. Am I better off leaving the pellicle intact or topping off?
Anecdotal Observations: My co-brewer's son works for The Bruery. With their pellicle beers in a barrel, they sample by pulling out a nail from the cask. They want to avoid disturbing the thin membrane . . . essentially accepting air in the headspace. The one time I put a racking cane into a pellicle beer the thin film immediately broke up (sank?) and did not re-form.
I have disturb a pellicle many times, to have it reform or been rebuilt. At this point though, I'd say throw in your extra wort...you'll destroy the pellicle, but you'll have very vital bugs to rebuild the pellicle, if needed. They built the pellicle in the first place because of the oxygen in your headspace, so it makes the most sense to remove it. Topping it off will 1) kill the headspace, 2) give a full batch when its done and 3) kick fermentation back on and add CO2 and lower O2 into new headspace.
Yeah, I sort of figured that breaking the pellicle by adding fermentable when the yeast are still young will not be too problematic for these reasons, but figured I'd bounce it off the rest of you.
