On the flies, I use PDZ mixed with sand on a poop board, and have no flies in the coop. I scoop every one to three days. There are only 8adults in there now. The youngsters live in other substandard housing...but flies aren't much of an issue. Did see some Poultry Protector at the feed store and bought it just in case. It's active ingredient is potassium sorbate and it says it is non toxic. But several of the adults have messy heinies, and the fly strike was scary.