cmom - When you throw DE on the pine shavings, do you mix it in with a rake, or just let it set on top the shavings and let the chickens do the mixing?
I'm doing around 2-3 inches of shavings. Works great, especially once I have enough DE - It never smells bad.
I don't think you can have it too deep, mostly because the chickens pack it down by walking on it.