I am a fan of Harvey Ussery, who deep litters his hen house and runs. Basically, he, and I, create a compost pile in the run during the summer and fall, and clean it out directly to the gardens the following season. Use roughly 1/3 green stuff"nitrogen heavy chic poop) and 2/3 brown (carbon). I use some of my garden waste, a bit of straw, pine shavings, and loads of fallen leaves. The chicks enjoy the treasures they find all winter long. On rare occasions when there are odors, mixing a little pine shavings in fixes it right up. Our run is 8' x 16' and houses 5 pullets. Don't know how other fowl do in this system.
What i have heard about sand is that the urea part of chic poop gets into the sand and eventually creates ammonia. Respiratory problems are a common result of exposure to ammonia.