I have several melomels in 3 to 5 gal carboys on oak which I wil shortly be racking to tertiary carboys and I am concerned about keeping headspace to a minimum. I have had a half-filled 1/2 gal container of melomel turn brown in about a month and I am very concerned about this issue. I would like to top off with other similar melomels but I don't have any on hand. I was thinking of using vodka diluted to 13% ABV. What do the big boys recommend? Oh, I did try to search this but couldn't find much.