What could be more pleasant than a corner of water in the garden near the terrace, which is more animated by the composition of two tanks at two different levels. Through an example of realization, let's discover how to realize the whole.
In this example, the pond is composed of two large rectangular tanks built into each other. The first, high tank is the largest volume of water. The second, lower level, is nested in a corner. At the back there is a planter and a technical room.
The upper pond
The upper pond is the largest volume, the height of the edge corresponds to the height of a bench to sit at the water's edge.
It receives the filtered water in the back left corner and has two overflows in the front right corner, consisting of two tubes that return the water to the lower pond. Thus, the level of the upper pond does not vary. On one of the overflows a vertical suction pipe for the bottom water is fixed. In case the overflow gets blocked, a gutter is placed in the corner to ensure an emergency overflow.
A drain is provided at the bottom of the high pond towards the garden. This is closed by a plug.
The low pond
The lower square pond is placed in front of and partly embedded in a corner of the upper pond. It receives the water from the upper pond and acts as a buffer by absorbing the variations in water level due to evaporation. An overflow towards the garden is installed at the back right in case of excess water following winter rains for example.
At the bottom, a tube connects the pond to the technical room to connect the water circulation pump.
The technical room
The technical room of the installation is placed behind the low pond. An electrical area with a bar of waterproof plugs is provided as well as the arrival of the piping bringing the water from the lower pond. It receives the filter and the lighting of the pond.
The pump is calculated to circulate the total volume of water in a little less than an hour. In our example the volume is about 4m3 and the pump 5.5m3/h. The pump will be slowed down by the length of the pipes and especially by the filter.
The filter is sized accordingly. It is equipped with an ultraviolet lamp to prevent the development of green algae.
A waterproof lighting system is installed to illuminate the bottom of both ponds.
The plants
The deep pond will host a water lily and floating plants. Beware of the obstruction of the overflows by these plants.
The lower pond with its shallower depth will host tall plants such as marsh iris or horsetail, lower perennials such as water marigold whose pots will be enhanced by a cinder block and submerged plants such as milfoil.
The plants are planted in pots with holes filled with a potting soil for aquatic plants with a thick layer of pozzolan on top to prevent the soil from going into the water and the fish from stirring up the soil by digging in.
Getting started
Take advantage of the fall and winter months for the work and prefer early spring for the start-up of the pond. The sun is not yet too strong and the heat is not too great, so it is a good time to start and install the plants.
