I am new to chicken keeping, and this is my first batch of chicks. They are almost 3 weeks old now and everyone seems very active and healthy, running around, eating, drinking etc all seems normal. But I have noticed both when cleaning the brooder and when hanging out with the chicks that there are some very "sloppy," kind of dark stools. They are getting medicated feed, water is changed at least once a day (usually twice), and everyone seems healthy but I just wanted to make sure there wasn't anything else I should be doing to help them stay healthy.