This project was a long time coming, I transformed a platform we had built for a water catchment tank into a 1400ish gallon fish tank using a EDPM liner.
The system currently has 4 ebb and flow beds but this is not true aquaponics but rather an aquatic system using a aquaponics component as a bio filtration system.
The body of this is built with 4×4 pressure treated lumber designed for ground contact. The first layer is 4 inches below grade and held into the limestone with 12 inch hot dipped galvanized spikes, which were aided in penetration by hammer drilling into the limestone layer. The other layers are each attached with 20, 6-inch galvanized spikes per course (5 per piece of lumber). Translation it isn’t going anyway.
Plans now include creating a floating plant island to prevent floating plants from being pummeled by the overflows and aeration wand. Adding cinder block towers and benches for emergent vegetation and of course adding a lot more fish. We also need to do some plain old landscaping around the area to make things look better now that the heavy part of the project is done.