The guys I make wine with never add commercial yeast, they let the native yeast do all the work. I've been adding yeast and turns okay fine. this year I won't, only fifteen gallons. I ferment in bucket and transfer to glass after two weeks. My lids are snap tight with grommets so I can use airlocks/bubblers to see if they are still fermenting. all's fine thus far. SG after two week is slowly going dry. Seems like it's taking longer to reach a SG of 1.000 or less with native yeast though.