Kathy, what
dry food do you feed? I know some foods make it smell worse than others.
We started using the clumping litter again vs the clay. We always used Tidy Cats and/or Arm and Hammer, but I saw a commercial for this new Fresh Step clumping and we have had it in both boxes for going on 2 weeks now and I can't believe it, the boxes hardly smell! We use the Arm and Hammer baking soda stuff to freshen the boxes, too.
Do you have a ktty that doesn't bury it? Sometimes they do that to "claim" the box and leave it uncovered.. my kitties do that sometimes.