At what age do I switch ducks from chick grit to poultry grit? I have been searching high and low to find the answer but I just come up with answers for chickens. They will be 6 weeks old tomorrow. My ducks need the grit at the moment as they are still inside because the duck house/run my husband is building won't be done until next weekend. They also won't be able to free range because in the state of Florida Rouen's and Khaki Campbell's must be in a fully enclosed pen at all times. So I want to make sure they are getting the right grit.