I went on a week long vacation and when I got back, my kombucha was covered in little black specks almost like super fine coffee grounds were sprinkled all over it. I threw it all out, boiled my jug, and tried again with a culture from a clean batch. Obviously I didn't sterilize the container enough and the black specks appeared again. I'm fairly certain this must be a kind of mold, but does anyone know what kind it is? I've never seen it before.