Aquaponics Design

This is the initial design that I produced with SketchUP.

The fish tank is on the left, and the fish poop and other effluent gravitates to the bottom of the tank where it is pumped to the plant tank. The plants, floating on styrofoam "rafts", absorb the organic fertilizer, and return clean, oxygenated water via a waterfall drain back to the fish tank.

The four foot deep fish tank will be three feet below grade with a foot above the ground. The two foot deep plant tank will sit on grade. Excavation will be the toughest part of the project and includes trenching to the house for the electrical conduits running to the water pump located at an enclosure at the end of the plant tank.

The tanks will be made of pressure treated plywood, reinforced with West System Epoxy and fiberglass fabric, and coated on the inside with a product called BrewCoat, which is designed to coat the inside of potable water tanks. The system will hold a combined 1,330 gallons and will be pumped with a 1000 gallon per hour water pump, that will be attached to a timer so that the water periodically circulates 24 hr/day.

The fish tank will be lined underground with polystyrene panels for insulation, and a grid floor with be set at the two foot level which will allow fish to go to the bottom of the tank to avoid cranes and raccoons, but will stop kids from sinking to the bottom of the tank if they fall in by accident (or on purpose).

Joanne wanted me to make some raised planting beds for vegetables, but we can have fish with our vegetables with this rig. I have the material budget at $1,100 and 11 man days will be required. And there is no particular credit to the man days even if a Mountain of a Man is doing the work.

The big contingency will be if I hit ledge when I dig the ditch for the fish tank.

If everything goes well, this system should be in place in the backyard by June, and we will stock it with Bluegill fingerlings and grow tomatoes and cukes. 
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I like the idea of the Bluegills because they are a hardy fish found in local ponds, and the kids may like to catch them for fun.  You could go with Koi or Goldfish if you wanted an ornamental fish tank, or you could stock with Tilapia or even Rainbow Trout if you wanted to raise the fish in the system specifically to harvest as food.
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Doug Maxfield, who used to have the second best Blog in cyberspace, northshorewaterman.com, before his last post some time ago, kept a largemouth bass, Bassford, in a tank in his living room for six years, so that is an option, although I would think that Bass could outgrow the aquaponics tank.