Yeah, you can place the cube right on top, buried half way or bury it so the top of the RW cube is flush with the top layer of pebbles, the choice is yours. I wouldn't completely bury it though....

You can also make a drip ring using a T with some tubing. A drip ring would be the best method of saturating the net pot with pebbles, as opposed to having it drip in one area or side....

(I can't wait to go back to hydro)....(sigh)........

CGI::::::