I am planning on adding a starter (built up bottle dregs w. Brett and bacteria) to a one gallon batch of finished Mild. I don’t want to leave much headspace in the one gallon glass carboy but am not sure what to expect with a sour starter like this. Any thoughts?
You could purge with CO2 if you have access to that. If not, you could add a small dose of sugar or DME to kick off some active fermentation in the beginning. That would help use up and blow off oxygen from the headspace.
I’m more concerned with the amount of krausen. Is this normally an issue with secondary fermentations? I wasn’t planning on using a blow off tube.
Gotcha. I wouldn’t expect much of a krausen from pitching bugs into a finished Mild.
I don’t think you will have very much krausen either.