I found these plastic 30 gallon drums that are said to be food safe and "great for soda and juice" so does this mean they will also be okay to ferment in? I'm just worried about the air permeability. It says the plastic is High Density Polyethylene. I have only been doing 5 gallon batches but now want to so something about 3x larger and wanted a cheap fermenter.
No .Don't scratch plastic. Bacteria thrive in deep scratches. Clean plastic with a soft cloth. oxiclean or an equivalent thereof works well for a 24 hr soak for a stanky(non-glass) fermenter as well. Brushes are for glass.
"Yes, I am a pirate two hundred years too late. The cannons don't thunder there's nothin' to plunder,
I'm an [under] forty victim of fate, Arriving too late, arriving too late."