ok from my experience with growing (of course i have grown outside and am converting to growing inside this winter) i would not use the root hormone anymore ... your plant seems to be doing good but just seems very short to me ... just my opinion... and before i tell you how to build the fixture are you familiar with electrical wiring?? how many light bulbs would u like me to design the fixture for??? and also try backing the lights up to about 4" and see if that will make the plant stretch or are you going to lst ???