I bought a bag of grit at the feed store for my chicks. They're 3 weeks old now. I read somewhere that if you feed them anything other than chick starter (grass, bugs, scrambled eggs, etc.) that you need to give them grit to help digest it. But the grit i have looks pretty large for babies. Would it be safe to feed to them, or do I need "chick-sized grit" (I didn't see it at the feed store)? The last thing I want to do is kill them with kindness.