Not sure if u got ur ?s answered yet...i just saw the post. Do not just fill the net cups. Trust me! You MUST fill the entire column with hydroton. Even if u were to get lucky ur yeilds, temp, root rot ect. will set u back so far u might as well have one simple girl setup, not a complicated vert. The couplings used to join the 2 halves together. PVC or ABS will work fine. I would recommend gluing but thats def due to many bad experiences that were out of my hands(hint hint) Use h2o cement! Or risk it ur choice. If ur worried about taking it apart they sell the pcs that connect with a thread male to female=quick disconnect with using cement. Over the threaded pcs obviously u cannot use cement so use the silver h2o proof tape good luck