I am lagering a Baltic porter right now and it has been at 60degrees (chest freezer with a temp regulator) for 3 weeks now. I have two carboys; a plastic fermentation vessel and a glass one. The plastic one has some mold spores starting to grow.
My gravity isn't where I want it yet, so my question is; is this normal? And should I be concerned that this could possibly contaminate the batch?
Totally normal. I wouldn't worry unless you have big islands of mold growing on the surface of the beer, and even then you still might be ok. A little mold on the outside of a carboy or in the neck isn't much of a concern.
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I have that problem with my sauerkraut batches all the time, mold starts growing on the outside of the crocks where it is damp from condensation in the 'keezer'. I usually carefully wipe it off with a piece of paper towel moistened with rubbing alcohol.