Someone please correct me if I'm wrong as this is really just my theory. I believe that you could submerge the net pot just a little to allow the wicking action of the medium to feed the roots. I know this works with perlite but I've never used Hydroton before. The splashing from the bubbles may also be sufficient but then again I'm not sure. You could possibly even thread a wick throughout the pot which in turn is submerged in the nutrient solution.
These are just some of the ideas I've come up with before attempting DWC myself. They may not be plausible.