As with every Do-It-Yourself (DIY) project, an aquaponics system provides you with the ability to be as creative and resourceful as you want with the materials and the equipment you use to construct the aquaponics system of your dreams.
However, I must point out that you must be very careful when selecting the vessels that will hold your fish and plants.
This part is very important, this is where a lot of folks fail miserably and murder their results, so you really need to understand and do this proper way!
I normally encourage people to use recycled materials, but you have to be careful with barrels and other large containers that may have been used to store chemicals.
You must always insist on getting only FOOD-GRADE plastic when you are buying barrels.
We have found food-grade plastics to be the best choice for grow beds and fish holding tanks because it is sturdy enough to support all the gallons of water you will add to the fish tank.
Thinner plastic vessels tend to crack and bow while the food-grade plastic will not, as long as you construct proper bases and supports.
NO TRASH CANS!
You may have seen some aquaponics system built using trash cans for the holding tanks. I do not recommend this, although using a container that resembles a trash can is OK if it is made of a strong metallic alloy such as stainless steel that will not easily rust.
Avoid adding any copper to an aquaponics system because copper can leak into the water and can cause problems later on.
If in doubt, apply a liner to the barrels to prevent chemicals from the surface of the barrel from leaking into the water.