What are the 11 1" pvc pieces for?
 

What are the 11 1" pvc for? I thought the bottle tops would fit inside, but they don't.

How does the system drain in the 11 plant system, and where do you attach the hose and pump.

what is the hole for on the top? Does it drain out a tee?

That's what the 1" thin wall pieces of pipe are for so a bottle cap will fit.

When the pump shuts off the water in the garden drains back through the pump. The hose from the pump connects to a tee with a 1/2 inch hose connector.

To prevent a siphon effect.