My System Consist Of A 2x4 Ft. Ebb & Flow Tray And A 20 Gal. Nurt. Tank Which Floods The Tray 15 Min. Out Of Every Hour. Water Depth In The Tray During The 45 Min Passive Period Is Approx. 3/4 In. Flood Depth Goes Up Gradully To Aprox. 2 In. I Grow In 6 In. Pots Filled With Hydrocorn Clay Pellets. Im Starting Out With 18 Pots, How Many Should This Be Thined To When Flowering?