I am going to suggest running a smart pot setup with Coco coir chips. I am guessing you could run a 3x3 with 9 and have a very even spacing. You could run 6 as well which is what I do in my test room.
I am not sure of your goal, but I certainly see no issues getting an LB out of that 3x3 run perfectly. Of course you'll need the right strain to do it with.
This what I would use for a grow bag or the like. Does not have to be exact but a good size for that depth of tray and will fit your numbers no problem.
Using this setup you can also use your dripper rig in the beginning in case you don't wick far enough up, but I imagine you'd still be fine. That you'll have to experiment with.
http://www.amazon.com/dp/B002JUW7L4/?tag=skimlinks_replacement-20
There are a few brands of Coco Chips out. I'd say most places will want to sell you the fine pith that everyone seems to amend, but ignore what most think.
http://www.amazon.com/dp/B0049XH0FM/?tag=skimlinks_replacement-20
or
http://www.amazon.com/dp/B00DQ4P6YW/?tag=skimlinks_replacement-20
I use both with great success and never wash the stuff at all. You expand it in a Rubbermaid trashcan or the like, and within an hour your planting in it.
You will also need some Epsom salts to boost the mag and sulfur content for the first 5 or so weeks, or two and a half nute changeouts.
Feeding under your LED's is not going to be like it was using HPS. The positive is you're gong to save not only power, but money on food as well.
If you decide to go this direction hit me up, and I'll walk you through a run so you crush it first time out.
EDIT: forgot one point I also wanted to make is you should hold off on CO2 until you are sure the food for these strains is good. One little mess up and your frying plants in mere hours under LED's.