I personally deworm twice a year as a preventative. Chickens are going to get worms, not if but when. I rotate between Valbazen and Safeguard.Does everyone worm their chickens as a preventative or when worms are seen in the poop? If preventative, how often?
In regards to DE... I see no point in spending $$ on something that is not going to solve any parasite problem. There are plenty of safe products available that WILL do the job and cost a whole lot less. Twice a year I deworm my birds and at the same time strip coops and put down Poultry Dust. There's no messing around all year long putting DE here there and everywhere. My birds are healthy and the parasite population is well controlled.