I see that there are two pictures on Photobucket that are very popular. Let me say first that I think hydroponics is a waste of water and pollutes the environment. Which is why I kept working to improve the system. You’d do better to just use the insert cup with only a single 1/8th hole about an inch up from the bottom. Keep the cap. But with that said let me give you a few pointers. I used a mix of Styrofoam chips and perilite to fill the insert cup. The Styrofoam is simple packing foam you get from the recycling bucket. There’s a test you can use to see if the Styrofoam is the right type to use. Just pour water over it, if a lot sticks don’t use it. I use a piece of nylon hose as a bag to hold the mix of Styrofoam and Perilite inside the insert cup. Get some velcro strips and cut a short piece off. Use a piece on either side of the cup to hold the cap on because they do pop off. Mark the cap and the cup so you know exactly how the cup goes back into the tank (two liter bottle). If you don’t you’ll keep running into root death without knowing why. See the system is so small that any movement from the exact spot it was before changes how the air flow hits the roots. Changing that even a little kills off some of those very hairy roots and just might put you back to square one. Remember to use a piece of tape along the side so that when you spray paint you’ll be able to see inside. The system works very well but in the coming environmental crisis you’ll need something that doesn’t use a lot of water, electric or oil base fertilizers. Now the trays, a double action pump will handle four trays (32 tanks) per shelf (2' x 4'). Please think Green...mean Green. Using single cups with only one hole will do you just as well with a hell of a lot less waste and pollution.
GSD

Yes I know I'm rather gabby tonight.