As for the pots being big enough, I assume so, this is my first grow in this system so we'll see if it works, they're actually a lot bigger than they look because they are pretty deep.

Regarding the connections... my ideal setup had the pots be removable... I tried EVERYTHING to make this happen! I went through at least 100 different pieces to make sure it could unscrew, but no matter what... it was going to leak. Teflon tape just slowed the leaking... so I came up with an alternate solution. Although I did not use this in my current situation, it fits wonderfully... a 4" net pot fits perfectly on the top of the 4" PVC pots... fill em with hydroton, and let it grow. I just filled the pots with Hydroton regardless of the net pot idea because I was too anxious.

And as for the flex when it fills up with water... wow was that a surprise... I felt like I built it perfectly, then the first trial... I nearly gave up on it cuz there were so many leaks and those other plans never mentioned anything about leaking. But a little material called Plumbers Putty fixed that right up! All my connections are sealed with PVC Cement and then re-sealed with plumbers putty on the outside... it's really quick and easy and it stopped all the leaks.

The first pipe in the middle cross piece that has two tiny little air holes, is the over flow. It's set at a decent high where the water level will stop at all the pots, but if your system isn't level, some might flood before your over flow kicks in.

Overall it is a little less than 4 feet long and 3 feet wide... so perfect for a 400w. There's a decent amount of room between the pots, but I figured it would be enough considering you see some setups where the plants are less than a foot away from each other.

I hope this helped and answered any questions, and I'll find a way to take some pics of the inside of the pots. You'll be seeing updates every now and then of the system, I'll try to keep it current. Thanks. Shmoke on.