When you say "Drain all the water out (or transfer into another drum) then bubble it with a fan over the top (and a heater if you want) for a few days until it clears." do you use an air bubbler from a fish aquarium? If so what type?

I do have problems like that occasionally and either just let it settle for some extra days or heat it to around 50 deg C for awhile to allow the convection of the heat to stir and separate the water from the BD.