I had a similar problem, super hot here, chickens drinking like crazy, had layer pellets, fresh h2o, and oyster shells, free choice, they are new pullets not yet 20 weeks laying rubbery malformed eggs. I added a daily feeding of layer pellets(2cups) mixed with a cup of plain yogurt in a dog dish, and filled their quart jar chick waterer with electrolytes. I figured protien, calcium, and electrolytes is a good treat! Within a few days i'm getting nice hard shelled eggs. Granted this could be just the pullets maturing and working out the kinks, but I felt better doing something, and just wanted to be proactive and harden up the shells if possible so we could try to prevent any egg eating if we're not home to collect several times a day.Mine eat a ton of grass too, otherwise I cut out the scratch treats(was giving 1 cup to 9 girls daily) I still give them a cut open summer squash, some berries, or watermelon, and the scratch every few days, it was in the 100's all last week!