I had some leftover sand from a masonry project. I brought it down and piled it up where our run will be since I hear a lot of people on here talking about benefits of having sand runs. 2 questions though - 1- will I have to pick poo out of the run if it is sand to keep it clean? 2- how many inches of sand should I have to keep it a sand run? Right now I don't think it will be enough and will just end up getting scratched into the dirt. Thanks!