this is the first time i`ve ever made wine. i`m followng a recipe from a book i bought called- the home wine makers companion. its a blueberry wine. i also bought the wine making kit from this site. last week i picked the 15lbs. of berrys and put all the ingredients together, i pressed the berrys this morning and put the juice in the carboy. my question is how much air space should i have in the carboy? its a 5 gal. recipe and a 6 gallon carboy. do i add water to fill it, leave as is or what?