White Scum at top of carboy

[Raptor99]

I see some white nodules at top of a few of my carboys, mainly cider. They collect around the edges and eventually create a white film over the surface. They sink if they are disturbed at all. I haven't noticed any off odors or flavors, but I rack if it looks like it is getting to be too much.

I know that similar questions have been posted on this forum, but I thought I'd share a picture to see if the collective wisdom here can help me identify the cause of this. This photo is a chocolate cherry wine started on 12/8/20. The most recent racking was on 2/3/21, and I add Kmeta at that time.

 

[Rice_Guy]

White film going all the way across sounds like mycoderma. A few carboys not just one? ,,, Poor sanitation.

 

[Raptor99]

Could be mycoderma. According to this article, it usually starts out a small islands on the surface: Mycoderma aka Flowers of Wine : Bacchus & Barleycorn, Ltd.. I saw that in some of my ciders two years ago. What I see now starts out as a thin white ring at the edges. It looks like something different from what I saw before. So far there are not any off odors or flavors. I do not smell any trace of acetic acid.

It only appears in a few carboys. Most of them are fine. I am careful about sanitation, but it is possible that something got in.