I have a batch of white Plum wine in a secondary carboy... It has started to darken, mostly around the top 2inchs. Two things i can think of is, too much headroom... ( have no other choice for container ) so i know i have too much head room but i dont know what negatives that would/ could cause. Or Second i just didnt add enough absorbic acid in hte beginning... is there anything i can do to fix this or is nothing broken?