Backyard Aquaponics
A place to discuss aquaponics

You all have been a great help on my other topics. My question now is , as a general rule what is the best ratio of fish tank size (gallons) to grow bed size (square feet)? This info will help me greatly on my decision of fish tank design.

By the way I am very glad to see I am not the only with this AP obsession!

If you read through the Basic Info and Useful info sections of the forum, you will find entire threads about the subject of ratios.

And, to simplify things even more, instead of square feet of grow bed, we usually use volume for the grow bed as well.
Usually you will see the ratio listed as Grow bed to fish tank like 2:1 would be twice as much grow bed as fish tank (yes, I know you wind up needing a sump tank or some additional way to deal with water level fluctuations if you have a 2:1 system)

Anyway, if you want to have anywhere near max stocking of your fish tank, you will need twice as much grow bed as fish tank and additional aeration. Example. 300 gallons of fish tank would have 600 gallons of flood and drain media bed filtering for it and would probably need a 300 gallon sump tank to handle the water level fluctuations.

Does this help?

I know this doesn't really answer your square footage question but the truth is, it is more about the bacteria to do the bio-filtration than it is about the plants taking up the nutrients since everything can handle a fairly wide range of nitrates for plants while if you are under filtered, the ammonia and nitrite can kill fish quickly. Aquaponics is really all about the bio-filter, A system can run sans fish or sans plants for a period of time but without good filtration, it can all start to stink pretty darn quick. Also, square footage of growing space is also highly variable depending on plants grown, system pH, light levels, etc. There is no way to give a decisive answer as to how much plant growing space will be perfect for a system since a change in any of those and hundreds of other variables will affect the operation. Lots of growing space is great but not at the expense of appropriately deep grow beds. 12 inches deep is a good minimum for most situations though I think 24 inch deep grow beds are great too.

Good Luck!