Couple things I just wanted to throw out there before I forget. LOL!
The Fence Post cover I bought and used on that NFTsystem was from fleet farm (not sure if there are any out by you) and it was I think 16 bucks for a 8 foot piece...not to bad, and it's thick enough it's light tight also. I wouldn't use it again, but it wasn't to bad cost wide.
I did have emitters on the ends of those small 1/4 hoses that go through the top, they both sprayed the younger plants as mentioned, and feed the NFT. There is a Name for this type of NFT system but I can't remember it.
I have been working on setting up a large scale lettuce NFT system with 200 placements, for this I used vinyl Rain Gutter Down Spouts and cut 2" holes in it for 2" net cups. It's a bit deeper then I'd like,and of course, once I got done drilling all the hose, I found shallower stock available. They were under 3 dollars for a 10' length.
Also, I wanted to add about the air diffusers in the reservoir...
1) it helps to pull gases to the top as in an aquarium,
2) while doing so it creates surface movement in the reservoir helping to get are into the fluid, again as in nature and aquariums, surface to air exposure is very important.
3) it bring fresh air into your reservoir and which if you have a more eclosed system, is a pretty good idea.
Something I remember also, and is also why I asked about them being started plants or bought. When I first set up that NFT I used store bought soil plants, rinsed them near to death to get as much soil off as I could.
I had to completely flush my system out after that, I don't remember how long it took, but it really messed things up. So completely flushed out my system with bleach and water, fresh
nutrients, and put the plants back in..and didn't have anymore problems after that. I don't remember if my roots got that bad, I do remember yanking nasty handfuls off and rinsing the remaining roots realy good before putting them back in.
I did not have the plants in the system while bleaching..just want to make that clear. ;-)
Hope any or all of that helps.