I would be careful about adding too much lime to the coup and run. Lime is a caustic and having that on their feet all day can cause chemical burns if you mess up and add too much. When we lime horse fields we do it right before a rain if possible and don't let the animals back on it until it has rained on it and dried back out to keep it off of the horses skin and out of their mouths, I would assume the same would hold true for chickens since they scratch and peck around on the groundHave you considered adding lime? That' s what i used to add. It is amazing!