That's pretty bad ass. I'm going to do something similar with 8 inch PVC (just to give my girls a bit of extra root room). I'm going to do either do 12-18 plants with a setup like that under two 600w HPS lights.
Shit I wish you would post a tek up (step by step set up) for such a lovely system.
They're a little drropy but thats because the lights just came on. After the last harvest I started some new beans. Made a BIG mistake starting in a F/D system with rockwool. Once moved to the NFT system the rockwool held too much water and didn't allow enough oxygen exchange. The only way to solve the problem was to put the sprayers directly in to the rockwool and flood the cubes with oxygenated water until the plants get big enough. These are a little more than 2 weeks old and there are 8 BigBud fem seeds as well as (4) NLxHaze seeds. Maybe another 3 days until I can take some clones to ensure a future Mom from each strain then I'll go to 12/12 hoping for a good outcome.