I'm making fruit scrap vinegar using watermelon rinds, and after about 5 days it developed this weird white layer on top. I can't really describe it as a fuzzy mold, it's like this interconnected matrix of white scummy looking vines.
I did quite a bit of googling around and a ton of people have had this issue but there's never been a definitive answer about what exactly is going on and what to do. I thought maybe one of the experienced members here could put this issue to rest.