your gonna have to ask DD if he mean stem to stem or bulb to stem, some people thought he meant stem to stem, I believe he means stem to bulb. is original room has two different light layouts, one side is the oxox pattern the other is rows, its due to the room design. rows you can space things closer, because there isnt a 1000w bulb that needs to be placed inbetween the plants and have at least 8-in inches around it on each side
I have 6ft stem to stem and the plants have to be tied back or they will touch the bulbs and Im not growing 4 pound plants, and my plants are probably larger than DD but yeild a lot less, DD doesnt yeild 4lbs off a kush. STRAIN is the key to your spacing, I will quote JK who said its easyer to design a room around a strain than make a strain work in a room
IM on my 6th MPB run, and no plant smaller than 5.5-6ft wide isnt going to give me over 1.5per plant, so thats a 60-70in wide plant, two 60-70in plants would nee to be at least 6ft apart, 35in from each stem to the end of one sides branches
now consider a 1000w bulb needs to find its way inbetween those 2 plants, so add at least another 12 inchs equaling 80in, or 40in from stem to bulb
If I were you I would try to set your system up, where you can make a couple different holes in the 4in PVC to accomadate different sized centers, because I can only tell you what works for me, and it might not work for you
Your going to tweek this system once you have your first run, and find out what works for you. The system will give you some amazing results, but like DD did , you have to work at it just like you did when you learned on a flat garden.
youngdro, the smiths house, a 44 lbs ten plant was 10x25 or 12x25 I remember becasue its was the same size as my girls room, and we were laughing because she pulls 1/4 that weight