[rverdlm]

Thom is right, the best way to keep the black tank clean is to pour a couple of buckets of water down the toilet as fast as you can every time you dump. After you do this you should be able to shine a flashlite down the toilet and see the bottom of the tank is clean. If not dump more water until it is clean. If it's clean there will be no odor while you're looking down the toilet. We've been full time for 14 years and we use no chemicals and have no odor. I know when the toilet is full because the noise when flushing changes. I dump every week, but can go over 2 weeks when we don't have a sewer hook-up.