There are many threads on using sand and people seem to love it. I don't like how the dirt gets muddy from rain. However, dirt is what hides bugs, which they love. I use an enclosed run and if I put sand down, not only are they never going to get bugs again, but grass won't grow through that. Then again sand is supposedly good for dust bathing. Wouldn't you have to supplement with grass clippings, dried worms, etc. Then again, i don't know if grass will ever grow back with the girls stomping around daily. Seems like both have their merits and faults.