I am a partner in a Colorado consulting company and nonprofit that specializes in aquaponics. It uses fish in tanks whose waste provides nutrients to the plants. So instead of adding nutrients to the water, you simply feed the fish. We promote this on every scale, from window boxes all the way to huge commercial operations that make use of abandoned industrial sites to grow a lot of organic food ( and jobs ) in urban areas. Maybe some of you would like to take it to the next level, once you see how it’s done! http://www.accestoaquaponics.com and http://www.ecolonomics.org