I live in the NC Sandhills where the ground is nearly-pure, fine, white, quartz sand just like you'd find in a beach dune (during the Miocene this was prime oceanfront). From what I read, this will meet their need for chick grit nicely as they scratch around. But as they grow (currently almost 6 weeks), will I need to purchase larger grit? There are no pebbles, rocks, gravel, etc. here other than in people's driveways.