I've been using sand in the run and coop. My hens have been in the coop now for about 2 months.....I started using sand just in the coop, using hay in the run. After seeing how easy it was to keep the coop clean and maintained, I discontinued using hay in the run and loaded the run with sand. It's really great, easy to care for and the hens seem to get along just fine with it. My question is.... over time should the sand be changed.... do you just add more sand to the existing... any type of annual or semi annual maintenance needed?? Thanks for the suggestions.