I currently have two separate systems in my Window Farm, each of which can hold 3 plants.
Because the system on the left has an empty pot I actually only have 5 plants growing at the moment,...4 Basil and 1 Parsley. Each system uses a wooden dowel that I've hung from the ceiling and to which everything is connected. The net cups and clay pellets are held in upside-down water bottles with the sides cut out. The bottoms of the bottles are also cut out so each water bottle fits into the one below it.
You also need to cover the bottom section of the bottles to protect the roots and I've used black duct tape on one system while on the other one I took a bit more time and painted them turquoise which i had laying around. The upside-down water bottles are attached to the dowels with a combination of cable-ties and small wire ties. I've found that new electronic gear comes with plastic covered ties which are better then the usual paper covered bread ties.
There are two separate plastic tubes used. One is the vertical water lift tube that is attached to the dowel and runs from the bottom of the dowel to the top where it arches back down into the top plant pot in the stack. The 2nd tube is the air hose and runs from an aquarium pump to the water-lift tube. The end of this 2nd tube has a sports ball inflation needle on it and this air needle is inserted into a small slice cut in the vertical tube about 1.5 to 2 inches from the bottom. To attach the inflation needle, I wrapped it's threads in plumber's tape and forced it inside the tube coming from the air pump.
The mechanics of the system work like this, the vertical water-lift tube is open at the bottom and naturally fills with water to the level of the water in the jar. The air pump then forces air into this tube via the air insertion needle. Because the air rises after entering the water-lift tube, it pushes a little bead of water up to the top of the tube where it drips onto the top plant in the stack. Eventually this water will drip through all 3 plants and return to the jar. As the air pushes the water bead up the tube, new water enters the bottom of the water-lift tube replacing the water that is being lifted by the air bubbles. Once the tube is refilled with water, the air forces a bit more of it up the tube and through the system again.
Be sure to NOT push the air insertion needle too far into the airlift tube. You want the air to get into the tube but you don't want to impede the water from filling the water-lift tube. Also, placement of the slot to insert the air needle into the airlift tube is critical. If it is too close to the bottom of the tube, the air will take the path of least resistance and exit the bottom of the tube instead of pushing the water up the tube.
My first crop in the spring of mainly Basil was amazing and I got a huge harvest from it. I shut the system down for a while but am now back up trying a winter crop of Basil. My aim is to perfect the growing of Basil so I can start up a home Pesto factory which I make from the leaves. Pesto can be made in large batches and then frozen in small dinner serving size cubes for later use. And I like Basil. I use it a fair amount in food I cook and having fresh Basil on hand at all times is a great thing.
The video below was made in the spring of 2011 with an earlier crop I was growing and explains how the system works. There are also close up pictures of the components down below on the page.
The jar on the right uses 2 air hoses while one on the left uses only 1. The 1 hose system powered by the Elite 803 with the adjustable valve works much better for lifting water.
The new Elite 803 and the Elite 799 which it replaced.
The Elite 801 air pump
The air hose where it is inserted into the vertical lift tube.
The value coming from the 803 pump.
The pill jar acts as a muffler to cut down on the water gurgling sound.
Water being pushed up the vertical lift tube.
I used the GROW(7-4-10) nutrient solution for the basil which they seemed to really love.
Every time I cleaned my water containers, I used the Sodium Metabisulphite to sanitize them before refilling with water. Could be overkill but I had the stuff on hand from brewing wine and thought I'd use it to ensure cleanliness.