I honestly don't know what to do anymore. We have a 12x8 run (no roof on it) for our 8 LF. The substrate 3/4 minus gravel, but the poop is building up and just sitting on the surface. In about 2 months the floor of the run is basically a disgusting layer of poop and decomposing shavings. How the heck am I supposed to keep this thing clean?! They free range for a couple hours each day, and I feel bad putting them away just because the run is so incredibly disgusting. Do other people have this problem?! How do you keep your runs clean?