Siphonphobia has created a neat looking system using 3 interlinked IBCs, as he saw it as a cheap way to get a 2000 litre fish tank. The IBCs were cut with the top portion becoming the growbed and supported on the base below. He used a couple of different ideas as supports such as pine logs and metal rods, but quickly realised just how much weight you have to support. He purchased the pipe and fittings which were needed to link the tanks. Water was able to move between the base f the fish tanks though it is a good idea to protect the opening with filter mesh to stop fish being caught in the tap area. The fish tanks were stocked with sivler perch and some mussels were also added to the system.
Unfortunately the mussels found their way in to the pump and stopped it from working. An 8000 lph submersible pump with float switch was installed which is a little larger than was required, but easily fixed by placing a tee in the line and returning water to the fish tank, providing extra aeration at the same time. The advantage of a float switch is that when the water level drops to a certain point the pump will stop pumping water rather than completely draining the fish tank.
The growbeds are filled with expanded clay which is lightweight in comparison to other gravel media, though the supports underneath need to be fairly sturdy as the IBC plastic is not terribly strong in itself and will bow easily. As anybody will tell you having an aquaponics system will take you on a wonderful journey of discovery and there are many people from all over the world who willingly share their experience on the Backyard Aquaponics Forum.