Lately I have been accruing equipment for yeast starters (ie stir plate, flasks, etc.). My question is for a 1000ml flask what stir bar would you use. I realize a 1 incher should due but do most people prefer the type with the pivot ring in the middle or without the pivot ring. Just wondering which type is most stable, quiet and provides the best areation. Also, has anyone found a cheap source for stir bars.... they can be rather pricey for how simple a product they are. Thanks!