The somewhat unusual design came from seeing interlocking circular brick raised flower beds at a garden we visited. The main pond is about 3ft deep and flat bottomed. This discourages attacks by herons. A stiff galvinised wire is mounted along the top of the double bullnose blue capping bricks. This discourages predators but an attack (we believe by otters) left us with no large coy carp and the wire is now electrified! There are about 120 small fish in the pond.
The top pond is for plants only and we call it the plantarium. Pond water is circulated through a filter and some is fed into the top pond to feed the plants and purify the water. A couple of fountains help to aerate the water down below. The bottom pond has aerating plants that provide oxygen and also shelter for young fish. There are a significant range of plants in the ponds including colourful water lilies and Arum lilies.
Top up water comes from a piped rainwater supply from the rainwater harvesting system.