You mention a barn, which sounds large, I would advise a starter system
First, so you can learn the nuances. Also, dumb question, how does sunlight
Get to plants in the barn
Amen to that! It can't be understated what hands on experience on a small scale will teach you. You can read all the books and have the best information but the responsibility of live fish and live plants is a whole different ball game. Murphy's Law applies!
With my small scale RAS I'm still tweeking things and building different kinds of biofilters before moving on to a larger scale system. It should save me not only money but heartache when I take the jump to a large scale system.
That said if you already have the barn...
I would also add that learning the ropes of rearing fish in an RAS would get you better prepared for aquaponics. Many people that want to do aquaponics get it bass awkwards and really need to learn how to keep the fish happy and alive first before moving on to the plants in combination with the fish.
Also, dumb question, how does sunlight
Get to plants in the barn
Grow lights.
