I have sand in the coop and the run, but haven't had any problems. I think the idea of adding a BUNCH of weeds, grass clippings, leaves, even straw.... anything green on top of the sand is your best bet. It's what they're used to. Then, catch a few of them and place them gently on the green stuff. They'll be walking on the sand and getting used to it by accident. If even one of them likes it, the others will probably follow suit. Maybe some of your neighbors can donate grass clippings and weeds if your lawn is too short too cut. I hope you'll find a solution soon!