I'm working on setting up a prototype aquaponics demonstration environment, and was wondering what I could use for a cheap priced demonstration of an aquaponics research plant? The part I'm stuck on specifically is the tanks.
White plastic 20 gallon pails are available for a nominal price at many hardware stores.
If you are thinking big then think used totes. These large plastic containers with a top opening and bottom valve are often used to ship food grade vegetable oil or similar. Sizes come in 275 Us gallon or 330 Gallon.
My local recycler stocks these and used olive barrels which are smaller but more attractive.
As with any used product it is buyer beware in the matter of what was in them before and whether they leak. Olive barrels have a fairly distinctive odour that tells you what they were last used for.
Most people seem to use recycled ibc containers that were used to store food before. They are then cut in half so that you end up with two containers. Not elegant but it works.
Barrels, and other containers that are taller then they are wide tend to be less appropriate as they lack the water surface area you need for oxygenation.
If it's a really small system, you can get second hand aquarium tanks fairly cheaply. But of course they're harder to move around with all the glass.
Any aquaponic system is likely to be more stable the larger volume of water you start with. But then also it may take longer to get nitrifying bacteria and archaea into your system.
It depends on the size of the demo, but if you're going for 1-2 plants for a demo, you could run to the dollar store. You could pick up a cheap mop bucket or 12"x8"x5" or so Rubbermaid tub for your demo. If you're going for something larger, you can still get the larger rubbermaids at Walmart relatively cheap or you can get a few 5gal buckets from Homedepot. Also, like another poster said, you can often go to grocery stores and get the empty containers from the deli section.