Originally Posted by Night Stone
Can downy be used instead of Calgon? It was recommended by one of the workers at the RV dealer.
NO NO NO!!
THe worker was "thinking" of Calgon but said Downey instead. NOT the same stuff. Downey or any other fabric softener is a liquified wax. It coats stuff - and if you have a front loading washer you probably know (or should know) that the scummy waxy residue that liquid fabric softeners leave behind is the place where mold finds a happy home and makes front loaders stink!
You are trying to make your black water tank cleaner - helping gravity to drain away more of the nasty stuff in the tank, not create a new hazard for additional stink!
As a side note - don't use liquid detergents that contain fabric softener for the same reason.