We have a flock of about 15 chickens and several have recently started laying soft (shell-less) eggs. These girls were laying hard eggs previously. I feed oyster calcium, although they are really not interested in eating it. We are on a private well but have a water softener. I am concerned that the softener has taken too much natural calcium from the water and is contributing to their problem. I had one hen get sick this morning and had to be euthanized due to Peritonitis. I don't want to lose any more birds. Any suggestions?