1..width of trough (gutter) should be no less than 6".

2..water depth should be just a film..similar to pouring
a glass of water on a counter top..

3..without a cover for the gutter..Algae problems..

Oh another enthusiast, GREAT! I'm planning on doing the same idea, using PVC pipes as the trough.

My idea is that this system will be closer to a modified passive system than it is an NFT. since we'll be having like 2" of water nutrient going around the roots to "compensate" for the round bottom of the PVC pipes.

Appreciate input from anybody else who have actually tried this.

wampuscat: About the depth... I was worried about a film like in NFT because I've read that there are problems like the roots blocking the film, and nutrient pools and deficiencies, and oxygen deficiencies... So I was wondering how the film could work well?

When you consider the depth of the solution, the speed of flow becomes a variable. The reason here is that if the roots are subjected to violent agitation their growth will be affected. The flow like that of a silent stream will probably be safe since there is almost no agitation of the roots. On the other hand, the solution in the tube must move fast enough so that a batch of freshly oxygenized (or oxygenated?) solution replaces the old one within a short period. With a thin film of solution movement most likely will not be violent.

JT..the reason I mentioned the minimum 6" width of the trough was because of the roots blocking and causing backup of the nutrient flow..wider would be better..I have been thinking about using 12" "patio roof pans" but have not come up with a good cover lid for it..I have been using the 6" pvc fence post for several years now and really have had good luck with them..I grow mostly tomatoes,peppers and some okra..some of my tom's are over 3 pounds..

good growing
corky