We happened into an "oops" gallon of porch paint at Home Depot. Fifties era turquoise, and it works for us. I will tell you that when they splash some of those cecal poos on the walls it really shows up, though. Interesting topic, I have wondered if using anything in the pink/red range would be a problem or not. Not considering that for the new coop, just curious. Will probably look for another gallon of oops for the new coop.