The only concern I'd have is that the fish tank is probably not nearly large enough to house them until they are 3 weeks old. Even at 2 days old there's not much room in there for them to move around. You'll have to be very careful not to overheat them in such a small, glass enclosed space.
Chick grit is just smaller size grit then what you get for grown hens. If they are eating anything besides chick starter they'll be needing grit also.
Chick grit is just smaller size grit then what you get for grown hens. If they are eating anything besides chick starter they'll be needing grit also.