Take into consideration that this all happened about 4 years ago, but this is the sequence Codi and I went through.

Once we decided to make ago of it, it was time to get educated. I ordered a bunch of books and videos. We everything we could find on the Internet.

By far the best information came from Dr. James E Rakocy with his University of the Virgin Islands (UVI) System. While the rest of us have been having disasters, trying different things out, they have scientifically measured the effects of different ratios between plants, fish and grow bed size.

This link has everything – especially for those in the United States (fish, prawns, ponds, systems, etc).
http://srac.tamu.edu/

The core info I found here.
http://srac.tamu.edu under SRAC 430-43-; 4300-4399 -- General

This link contains a number of other good articles on re-circulating aquaculture.
http://srac.tamu.edu under SRAC 450-459; 4500-4599 – Re-circulating Systems

Initially I found that general guideline at MAXIMUM density of Tilapia was:
˝ lb of Fish per Gallon of Tank
2 Gallons of grow bed per Gallon of Tank
or in metric
250 grams of fish per 4 liters of Fish tank
and 8 liters of bed per 4 liters of fish tank

But if you read further, what you actually find is that the size of the grow beds/raft system at maximum density is tied to the amount of feed fed daily.

If you’re feeding a fish that grows slower, such as trout (9 month grow out with 1.1:1 feed conversion), then you have less feed input each day, so you need less grow beds.

Conversely if you’re feeding Tilapia at 1.7:1 and they grow out in 6 months, you need many more grow beds, or you must stock a lower density.

A 4 x 8 foot grow bed will remove 0.4lbs (+/- .2lbs) of feed per day (according to the UVI research). Using the UVI data, I found that a 250 gallon fish tank raising trout required 1.37 beds 4 x 8 feet (1.4 to 1 ratio), while the same system growing Tilapia requires 3 beds 4 x 8 (3 to 1 ratio).

That’s a big swing. In the end, the 2 to 1 ratio is a good average, especially if fish densities are kept below the maximum, or fish are started with fingerlings and the plant load grows as the fish grow.

So, we calculated the area of our greenhouse we were willing to dedicate to our initial aquaponics trial, and a 250-300 gallon (1000-1200 litre) fish tank with a 2:1 ratio to beds (1/2 gravel 1/2 floating raft) would work.

Choices of fish to raise:

Down South…no question, Tilapia is the answer and that’s what we went with.

Now for you folks up North:
1st Choice – Silver Perch (easy to raise, tolerate a wide range of conditions and grow fast, not prohibited in most northern states.
2nd Choice – Tilapia (similar, and easy to find in the U.S but will need heat in winter.
3rd Choice – Hybrid Stripped Bass (not as easy to raise, not as much info, but readily obtainable in the U.S.)

Next I looked at various system options, commercial kits, DIY systems, Barrelponics, Nelson and Pade, Aquaponics Made Easy, etc. I found that in the U.S. a packaged system was to expensive to even consider what with fish tanks costing $1 to $2 per gallon of tank. I found lots of recommendations to use 55 gallon plastic barrels, IBC Totes, Stock Tanks and More.

I finally wound up going with a 300 gallon rubber maid stock watering container, sturdy and no glass to break and they last forever...really
Hope this info help anyone who reads it.