TheDriftlessDistiller

I've used Patco and Olive Oil. Neither really helped with overflow during the fermentation, but they both helped prevent foaming in the distillation. I prefer olive oil as it's cheaper and a little goes a long way. (I also use it as a machine oil for manhole fasteners). For fermentation, I dropped temp to about 88F compared to the 94F I usually start the 600 gal. fermentation at in our open top fermenters. The ferment reaches the very top of the fermenter and settles back down. I did distill at a distillery where the vessel didn't have adequate headroom so it always turned into a school science project and spewed over the sides.

I'm a little late to the responses here, but I have had this same cap thing happen many times, and just now jumped to the forum to see what others had done. When it falls to the bottom, it ferments out great, when it's on top, it can take much longer than your production schedule allows to ferment and often takes re circulation/agitation. A good way to test this is to test the SG/Brix the day before, then pump it into a stripping still and agitate without heat on and turn off, then check the next day to see if it's fermenting or if your SG/Brix has changed. Currently looking at agitators to be used in the fermenters.