You don't need to use straight all PDZ in your poop trays. I laid a full bag of play sand in the bottom of my tray and then the PDZ on top....works GREAT!Thanks -- I told my HB that I figured kitty litter might have added chemicals to it but he suggested to check with you guys. We have decided to stick with the PDZ. It was so easy to clean up this morning -- amazing. I was short 2 bags and my supplier was out. Major invested at first because of how big my poop boards are. But can see that once we are set up we'll be good to go. Just have to add to it once in awhile.