[RGordon]

I don't think you said if you repaired your leak in the black tank, but I have dealt with foul odors coming from the basement. They come up right through the pocket doors going to bedroom. Mine developed a leak right at the base of the toilet. Plastic of course, broke right at the base and only way to repair it was to install a wax ring like goes in a residential application. This took care of the leak that was leaking down on top of the black tank and no more rocking of the toilet. Baking soda goes a long way in eliminating odors once you dry out the area.