You need to match the size of ur root chamber to the output capacity of the fog, U should be able to fill up the chamber completely with fog, not just the bottom, What fogger are u using?

Keep in mind a DWC grown plant sucks up massive amounts of water, and if your Nute solution is low in PPM the plants will be flushing out all those nutes the fog just gave it. But then again there is always a balance you could find between the two. A DWC/fog method kinda seems redundant becuase there 2 methods on completely different extremes of Hydro. One Utilizes alot of water and alot of nutes, while the other is the exact opposite, fog requires little water and low ppms. A DWC/fog method would be more like a DWC then fog type set up which im sure your not really trying to do.