I am reading a lot of posts that mention DE- it seems like it is an important part of keeping chickens? My H wants to know if it is a waste of money? Would love a little more explanation. Seems to be used in nesting boxes, runs and can be put into feed? We are going to have 3 chickens in our coop in about 5-6 weeks and then hopefully a few more chickens in the spring and just wondering how much of it we would need to get as well as do we need it? I am sure there will be varying opinions but I want them all!