Yes eating the sand will give them a bit of grit they will need. If you give them spaghum peat moss be sure it is where it will stay dry. When wet it is a perfect fly manufacturer. I mix a bit of sevin in mine so the bugs do not bother them to bad. I usually wait until they are a couple of months old for the sevin. By then they quit eating the sand pile and figure out what it is for. Your little ones are about the same age as mine. I have NH, Dells, BRs, olive eggers, ameracuanas, and orps. Yikes 30 of them str. run. I am already seeing sooooo many little roos. I hope to have a flock of at least 10 hens but could handle more. Gloria Jean