What is the white powder on my air ionizer?

I have an ionic pro turbo air ionizer, and it has worked well for about 4 months. Suddenly it seems to be creating a white powder that accumulates on the inside of the unit, and it needs to be cleaned daily. Even after a thorough cleaning, the blades and inside of the unit will be covered in this white powder within a day or so. What is this powder? How can I keep it from accumulating?