Ok, plop your WELL rooted clones in the BOTTOM of your net cups with hydroton around your rooter. Now set the water level just a small bit below the bottom of the net pot and set the bubbler right in the center. That should splash the water up to the roots in the net cup really slightly and inspire them to come down.

Once they do you want to keep lowering hte nute level leaving 1/3 or more exposed to air.

Luck!