This is the top of my carboy of H3 Merlot. Smells and tastes OK. Haven't measured SO2 recently, but I racked and added 1/4 tsp of KMEta during the holidays after MLF was done.
Surface concerns Ive dealt with that this could be: -I’ve had the tartrates float (after a tartaric addition), but they looked like verytiny little specks & snowflakes. - had carboys with lees heavier then typical “fine lees” that would break off and rise to the surface, and the visuals varied. Was cloudy/stringy once. Another time was kinda spotty. -oily surface that if left for extended period formed a “skin”. -and have had full blown mycoderma once. Hard to get a good representation from a pic. Majority of the time I had surface stuff was in high ph wines. But Every occurrence was identified within this checklist -tartaric added after AF -headspace -significant lees remaining -Higher ph
Do you have a tight seal on your (filled) airlock? If your leaking air continuously then you have the perfect environment for Mycoderma which (hard to tell with that pic) but it could be the start of. Spritz the top with sanitizing solution just for safety sake.
