So I'm pretty sure I have Marek's in my flock which I know would make egg laying decline drastically. But I also think my hens have a calcium deficiency. I've been giving them their eggshells back and they have oyster shells all the time but it doesn't seem to be working very well. I was wondering if I could just buy some calcium supplements from Wal-Mart or somewhere and dissolve them and put it in their water? Update So apparently it was a calcium deficiency. The supplements from Wal-Mart worked well, just dissolved a pill in water and placed it in their waterer. The next day I got 3 extra eggs, hard shells. It seems to be improving their laying slowly but surely. I dropped down to once a week and I am going to try and switch to a different layer pellet. But thanks for all the advice.