Another thing that works to clean the tanks is to purchase some Calgon water softerner in the Grocery store. It is sold in the detergent aisle. We just put a capful in the black tank, fill it with water, let it sit and then rinse it out. You would be surprised how dirty the water is at first and then crystal clear when your are done. We also have the black tank cleaner from another trailer we had that is basically a hose with holes in it that you put down the toilet and run water. It always did a fine job but with the sani-con we haven't had a need for it.
