I've been using a bit of apple cider vinegar in the drinking water since having a similar problem. Some of them seem to get *too* interested when the grit is renewed so I've begun giving it only when I offer treats, in their blue plastic livestock bowl. My layer feed has grit and oyster anyway!
The ACV is about 1 Tbsp to a gal of water. They all like it.
The ACV is about 1 Tbsp to a gal of water. They all like it.