I LOVE, LOVE, LOVE rice hulls for the coop. I am fortunate to be able to buy them from a very small feedstore in Austin. The owner travels to a town several hours away to pick them up. They are hard to come by. When I first started using them I was using the wrong thing - composted rice hulls. You want the dry, uncomposted rice hulls. They dry out really fast if they get wet and, in my opinion, keep the smell down. I lay them down over sand. My coop is not enclosed, three sides are covered in wire (hardware cloth?) so it is very well ventilated. This very likely has some bearing on keeping the smell down. It's easy to clean. I sift through it and remove the poop. It is a most wonderful addition to the compost pile. It breaks down fast.