(I think I've finally gotten a title to make someone look at one of my questions, hah!) This is the southern half of our run. it is nice & dry with filtered sunlight. My chicken run sand is very "sick" in some spots. I have a really shady run, overhung by beech & hemlock trees. It's the only semi-level spot on our 2 acres, apart from the driveway. This pic shows how shady it is midday, midsummer: It still has a slope of about 15 degrees from front to back I excavated 15 cubic yards of clay & stones from the existing chain link run to turn it into a chicken run. This was the sand just layed. It shows the retaining wall blocks on the terraces. The terrace near the post is the shadiest, stinkiest one. The run now has 2 ft. of limestone gravel, an 8 ft graded French drain in this, and weed cloth in between with 12-24 in. of mason sand on top, throughout. It has a structural tent-shape roof overhead which is sort of latticed, with a bit of solid wood at the top, like an umbrella, attached to the central post. This allows snow to drop through, to minimize weight on the structure. Here's my roof, to show it off, and to show how lit filters sunlight even more. We couldn't roof it solidly, due to the galvanized steel dog run poles not being able to support a roof's weight. The hill it's on is shale, and digging down more was not an option either. 3/4 of the sand in the 175 sq ft. run is fine. It get a couple hours of sunshine & dries out. This is also the part near the French drain. I scoop poop out of the whole run every 48-72 hours with a small rake & cat litter scoop. The back part of the run, which is at the top of the grade, is the very shady part away from the drain, and I deep-raked this today, to find it grey and very stinky underneath. It smells exactly like the sand at a lake shore or pond shore where the trees overhang and you get a "mucky" sand which smells. The chickens rarely run there, as it is the top tier of the 4-level terraced run. There's never a lot of poop to scoop there. So, I raked it & turned it over.. it's obviously full of some sort of wet-sand bacteria. Will this make the chickens sick to eat it? How do I fix it? Ideas, please !!