What is the best method for cleaning the inside of a 100 gallon , bain marie stainless steel pot.
depends on what you're trying to clean from the surface. But if it's normal Brewing stuff we have had very good luck with PBW. I believe that's what most breweries use to clean their tanks as well
As well as "what" you want to clean off, "why" do you need to clean? Does the pot have a CIP ball?
If you need to scrub by hand, can you reach inside? If you cannot easily remove by hand or have a CIP system then you may need to fill the pot with cleaning chemicals. (some people freak out about chemicals but dihydrogen monoxide = a chemical = H2O = water)
I did not think it was a big issue but I wanted to be sure.