I use three systems all with no dirt. 1. A drip hydroponic system. I use a 35 gallon rubbermaid barrel fillrd with water and nutriants. A pump in the water, a timer. A hose is attached to the pump, the hose is streached across two towers on plants. Perlite and coconut shells (shreaded)
2. Areoponics. A 20 galon reservoir a pump, a timer. Both of these setups need to be refilled every 2 weeks.

Be sure to plant where you can water with fresh water. You don't want to eat food grown with non-potable water!