Compare them with any other form of vegetable gardening technique.
Heres part of a writeup from the first site Id like you to visit.....
Enter aquaponics, a system of food gardening that has a small but growing fan base, not least because its advantages seem almost too good to be true. An aquaponics installation requires no soil, scant water (2 to 10 percent of what is used in the average vegetable garden), a modest financial outlay and minimal maintenance. Theres no dealing with pesticides, and the system is sustainable and easy to set up. For gardeners conscious of the need to slash their water use during Californias drought, or those with little or no land, this method has a lot to offer.
The use of metal halides in aquaponics is highly recommended. This is becaus....
A journal of modern day pioneers forging a new frontier in the city through intensive agriculture and extreme sustainability in urban homesteading....
http://synaptoman.files.wordpress.com/2008/01/siphon-loop1.jpg?w=519&h=392
And this is the guy who designed it...
