For 3 week old dragons, you shouldn't have them on sand at all, they should be on paper towel. As for the water drip, there isn't any point getting one of those as all you need to do is mist the dragons 2 - 3 times a day till they are several months old and eating greens daily. Babies hydrate very quickly and need to have water available at all times. If they will drink water on their own from a small shallow dish, all the better. You could use the water drip thing but for the extra cost, it's not worth it since there are much cheaper ways of doing it that work just as well.