Sand will work Great in a open uncovered run, because it will work the poop through when it rains like a filter, but under a covered run, you will need a retainer wall like in KuntryGirl's Pea run, or the sand will just wash away. Hay will mat down and make a bigger mess. I have the same problem in the enclosed barn, because it doesn't get rained on. The only thing to do is till it in or turn it under with a shovel. The barn is on a dirt floor. If it were on cement, I would just pressure wash it. Thankfully, everyone free ranges and only sleeps in the barn at night. Since the turkeys make the really big poops, and they have a really high roost, it isn't hard to just throw more sand under it or shovel it out. Eventually, we'll have to till it up and push it out with the tractor and refill with more sand. The advantage will be that it will improve the pasture it gets dumped in. Dry weather isn't bad but it starts to smell in wet rainy weather, when the ducks track in a lot of water. I don't use waterers inside. they have a man made stream just outside the door.