I've search this site and read countless reviews on both CW and Amazon and I can't see which one is the best. Which chemical do you think does the best job and why?
I wouldn't recommend newsprint or aluminum foil, but anything softer than that is fine. The black tank is not a processing point. It is just a holding tank.
By the way, I can think of several other reasons not to recommend newsprint or aluminum foil which have nothing to do with the tank.