If I understand correctly, this 'aquaponics' solution:
* does not require arable land, because the plants grow on containers filled with stones through which water constantly circulates;
* uses an order of magnitude less water than traditional agriculture, because the water is constantly recycled back from a nearby fish tank, and because the rock layer prevents water from evaporating;
* allows plant density (i.e., number of plants per unit of area) an order of magnitude greater than traditional agriculture, because plant roots don't have to work as hard to find nutrients, so they grow straight down;
* does not attract traditional bug pests or weeds, because there is no wet soil to attract them;
* makes plants grow much faster, because they're getting a constant supply of nutrients fed through the water recycling system; and
* is also an inexpensive fish-farming solution!
Unless I'm missing something big, this solution looks BRILLIANT to me. All it needs now is for a talented entrepreneur to come in, find an early-adopter market for it, and turn the technology into a standardized product that can be sold at scale.