So I've got 6 week old girls and I just started introducing them to yogurt and they loved it!! I'd like to start giving them some grapes and stawberries and such.......I've heard that a bag of construction sand is a good grit alternative, my question is, how much should I give them, how should I give it to them, and for how long?? While in the brooder should I just give it to them before I give the harder treats??? Your help is appreciated!