Hey all, our small flock is thriving and its very exciting. Our 3 infamous Silkies have been confirmed, rather loudly, to be boys. The 4th from that order seems to be pullet. 8 chickens in all...how'd THAT happen? Anyway, we have some leftover aquarium stones, the small blue coated kind. Are they safe to use as a grit for the chickens? Just wanted to check before I filled a cup.