I have a small 4'x4' coop with attached 4'x8' run. Since the coop is so small I use PDZ on the whole floor of the coop - makes poop-scoopin' a breeze! I have just 2 girls in my coop. I've used the same PDZ for about 6 months now. It still seems fine but I imagine at some point it's efficacy will fall and it will need to be replaced. I use sand in the outside run so thought to just sweep the used PDZ into the run and add 2 or 3 new bags to the coop. Just wondering how long people keep their PDZ before replacing it? 6 months? A year? Longer? Loooove using PDZ. Makes the whole chicken thing sooo much easier. Thanks for the tip, BYC peeps!