I don’t have a 10gal fermenter, so I have to split the batches into two 5’s. I clean and sanitize like a maniac. After I had them in secondary for a about a week, I noticed an odd film on top of one of the carboy sand not the other. Never seen it before, should have taken a pic.
So I went along my normal process, got em both kegged, carb’d and tried them did by side last night. Now, that was by far not a best effort. But it’s good. However, one of them, the on that developed the ‘film’ had a weird sort of after taste. Almost like a stale aroma or cardboard boxy. Sorry, that’s the only way I can explain it. It’s not horrible, but I don’t think I will be filling my buddies growlers with it.
Same and new yeast used in both buckets. Everything was the same with both portions of the batch.
Anyone have any insight as to what my have happened with that one half? I’ve brewed a lot of batches and this is the first time this has happened...I don’t know what I did

Thanks folks!
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