I put my 9 week old chicks out about 2 weeks ago, and they have just discovered the big girls grit, they are scarffing it down like crazy, should I take it away from them, so they get it in moderation, or just let them have at it?? there is maybe like 1 1/3 cup of grit there, between 11 chicks, they wouldn't confuse it for food would they??