one of many nft info sites to check out:

http://www.container-gardening-for-you.com/nft-hydroponics.html

ie, you can definitely do with a LESS filled pipe.. it's important to have plenty of oxygen for the roots as well..

nutrient wise.. buy online? general hydroponics, humboldt (organic)...?

im relatively new as well though...

don't set the drain up at all.
In NFT, you only want a film of nutrient flowing across the bottom. If the drain level is adjustable, you could set it up initially to allow the roots to grow out of their media. However, once the touch the bottom, you don't want any standing solution. it will eventually become oxygen depleted and kill (or substantially injure) you plants.
My first go at hydroponics I did the same thing.
I haven't gone that route since.

What grizzman is pointing out here is indeed an important detail.
NFT gullies or channels have a permanent flow that is between 1-2 Liter per minute, which is not much. But actually after a while when roots do expand, the actual level increases somewhat (as it doesn't flow exactly freely) and it's more than a film actually. And yet, you have the roots in running water and a intermediate zone with optimal root expansion, uptake and oxygenation. If using standard PVC tubes you haven't got a flat bottom and no groove either. It's indeed not the same thing. In fact there is a differentiation in terminology as well, the PVC tubes with a certain water level are called NST as in Nutrient Stream Technology. I saw this term firstly at the "tengreenthumbs' page" and couldn't agree more with the semantic differentiation. ;-)

Well, PVC tubes are OK and indeed tempting. I did a few setups myself because they were so easy to build. I didn't continue that kind of setups though, because plants weren't actually doing that fine in those. I didn't regret a second that I have switched to the real thing (as in genuine grooved NFT channels) actually too late somehow , as I am truly amazed about the growing rates and the vigor of plants in the later.

This is not meant to discourage anybody from building anything of the sort, but I guess it is necessary to point out the clear difference in functionality and expectation also.

Here is a link that might be useful: tengreenthumbs

I use vinyl downspouts for my runs.

Hey guys, thanks for the input, I won't put a drain in then! =)

Also, grizz, what do you use as a "lid" for the downspouts, or am I thinking of gutters?

would you mind posting a pic of your setup... I would like to keep all my options open and not regret any setup that I do or don't use. Thanks to all, you've been a real good help!

~hfg

for lids I cut up some spare pieces of vertical blind slightly larger than the downspout. I spot glue them to the downspouts with plumbing glue (the orange stuff) and then I seal them with silicon.
I only do that on one end. the other end I leave open and the water dumps into a short piece of downspout which drains back into my reservoir.
This year I also covered each downspout with aluminum foil to control algae. I added the foil later. next year I will add it onto the DS before I make the system operational.