Hello! I am getting my 25 cornish x next week and have a questions about grit for the chicks. how long will they need chick grit vs. "adult" grit? one store only sells 50# bags of chick grit which seems like too much but this is my first time doing this. can i use sand/something else for grit for the chicks? also something that surprised me from the feed store lady--she kept talking about selling starter/grower grit, finisher grit and turkey grit. i said "you mean feed?" and she said "no, these are different types of grit we sell." does this sound right? thank you!