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Pond   Installation

Installation of a outdoor pond

Installation bassin

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Before installation

How to choose your pond?

The first step is to decide what type of pond you want to build. In fact, we will not choose the same construction techniques for ponds for red fish, for example, as those of koi carps, or just for an aquatic garden. Maybe you only want a nice water point for the sound of a waterfall. Also think about the evolution you want to make to your pond over the years. A common mistake is to build a small pond, which does not allow after a few years to add fish or plants. In addition, a large pond is easier to stabilise and maintain!

There are 2 types of outdoor ponds: one preformed or one with a shell. The preformed pond is easier and faster to put in place. However, its size will be limited (ideal for red fish for example). The pond with shell will allow you to choose yourself its shape and depth. It will usually be larger than the preformed ponds (so carps can be kept there). Whatever your choice, opt for a pond of at least 5 m2 or 50 ft2 of surface! There are also mini-ponds consisting of a large container (half-barrel, jar, pottery...). These small decorative ponds are intended only for plants, we will see here only the types of ponds that can accommodate fish.

And what about the law?

The installation of a pond does not require any special work authorisation. However, it is better to declare your work at the town hall. In the case of condominiums, consult the specifications to know if you are allowed to install an outdoor pond.

Technical equipment

The pump

It aims to draw water from the pond to send it to the filter. We’ll install the pump in the center of the pond, slightly elevated so that it does not clog too quickly (placed on a large stone for example). As the pump and the filter are distant from each other, the power of the pump will be determined by the distance between these two elements ("discharge" distance). In general, the pump will have the capacity to suck up all the water in 3 to 4 hours maximum..

The filter

Its purpose is to clean the pond water. For this, it will retain organic particles suspended in water. These will be eliminated thanks to the bacterial cleansing colonies. Thanks to the filter, the pond will always have clean, clear water. It must work every day and all day as soon as the temperature exceeds 10 ° C or 50 ° F. The filter is installed directly on the bank (within reach of the electrical installation). This filter should remain accessible for maintenance but you can hide it among the vegetation near the pond, or even partially bury it, depending on the models. Put it on a sand bed for more stability and check its horizontality with a spirit level.

The water jet

water jet

The water jet is very important for the pond!

It is not a simple aesthetic element. The water jet will allow a good oxygenation of the water. It is a vital parameter for fish, and it will prevent the formation of algae. It can take the form of a waterfall or a jet type "fountain".

The layout of the material

Depending on the material you have chosen and the configuration of your pond, several solutions are possible between the pump, the filter and the jet:

the different layout of the material

The UV lamp

It is placed upstream of the filter. Its role is to destroy bacteria that could cause diseases and green algae suspended in the water. This lamp can be started 3 weeks after the watering of the pond, and this in order to let the biological cycles settle in this new ecosystem.

The plants

Water lily

A bud Water lily

The aquatic and shoreline plants are as beautiful as they are useful. Do not deprive yourself! They will absorb the nitrates contained in the water, thus limiting the proliferation of algae. In addition, they will shade the pond in the summer, which will prevent the pond from rising too high and evaporating too quickly. The plants on the banks contribute to the strength and stability of your banks and if they are high enough, they can also shade the basin. Generally, planting should be done between April and June.


To highlight the beauty of your pond or just to make it safe at night, you can install lightning. This lightning must be moderate so as not to disturb the day / night cycle of your fish. In the same idea, illuminate only certain parts of your pond, like the waterfall or a beautiful plant for example.

There are a lot of lightning for ponds: submerged spots (must not exceed 12 volts), solar emergent spots to place around the pond, floating light balls... LED lighting solutions are very interesting because they broadcast a pleasant light and consume very little electricity.

General advice

The shell pond

Pond made using a tarpaulin

Pond made using a tarpaulin. When it's done well, we do not even see the tarpaulin anymore!

Before installing your tarpaulin, cover the hole in your pond with a strong geotextile felt. This will prevent your tarpaulin from being pierced by a pebble. Cover this fabric with a perfectly waterproof tarpaulin. For this, use a PVC or EPDM tarpaulin.

Since you decide on the shape of your pond, we advise you not to go into too complex shapes to avoid sealing problems. For example, an oval shape will give a natural appearance and simplify the installation of the tarpaulin (width = 2/3 of the length).

To know the size in centimeters of the tarpaulin needed, measure the hole of your pond and count:

  • Length of the cover = length of the pond in cm + (2 x maximum depth of the pond in cm) + (2x50 cm for the banks)
  • Width of the sheet = width of the pond in cm + (2 x maximum depth of the pond in cm) + (2x50 cm for the banks)
  • For example, for a pond 3 meters long, 2 meters wide and 80 cm deep:
    Length = 300 cm + (2x80) + (2x50) = 560 cm (220 inch)
    Width = 200 cm + (2x80) + (2x50) = 460 cm (180 inch)
    It will take a tarp of 5.6 by 4.6 meters (18 x 15 ft).

The preformed basin

With this solution, you will not be able to decide the shape of your pond. However, there are many models among which you will certainly find your happiness! It is actually a molding of a shell. It is very resistant (no risk of being pierced by a pebble!), durable, ready to use and easy to install (in one day). Another advantage is that this type of pond can be installed above the ground or in the ground. The shallow areas are for planting and for the safety of children and animals. The deeper parts (from 80 to 200 cm (30 inch to 80 inch) are intended for fish: the deeper the pond, the warmer the fish are in winter and cool in summer!

Where to install your pond?

In general, favor a south-east exposure and avoid full north or south.

This may seem obvious, but it is better to remember: do not install your pond in a hollow in your ground, or down a slope: the rains could then run off and overflow your pond.

Do not set up your pond too close to the trees: in autumn the leaves fall into the water, rot and form mud; not to mention that some plant elements can modify the chemistry of the water or even make it toxic (conifer needles make acidic water, yew leaves or laurels are toxic...). However, the pond needs some shade in the summer. You will need to find the right balance in the distance between the pond and your trees: not too many leaves in autumn and enough shade in the summer. Finally, beware of the roots of some plants that may come to perforate your pond (bamboo, pine...).

Check the hardness of your soil before digging: the minimum depth of a pond is 80 cm (about 30 inch)!

Finally, know that the ponds are very attractive points for the surrounding fauna. So, you can see many birds or butterflies evolving around this one!

The safety of the pond

If possible, position your pond so that it is visible from your home. Never let children play alone near your pond.

For your safety, install the electrical power supply (connection to the central electrical panel or to a panel dedicated to your garden) in accordance with safety requirements, including the installation of a 30 mA differential circuit breaker and compliance with the standard NFC-15-100. Do not hesitate to call a professional if you lack the necessary skills (especially if you have to bury the cables when there is no current near your pond).

Your fish also need to be protected. You will not be the first to see all your fish disappear one after the other! Indeed, pond fishes are often victims of cats and herons. There are several methods to protect your pond fish. For example, you can install electrified wires around your pond. These threads will cause a fear reaction in predators who will not put their feet near your pelvis anytime soon! However, some people might be embarrassed by this method, which we understand and fully respect. Nevertheless, this method of deterrence exists and deserves to be quoted in this article. Free to everyone to do according to his sensitivity!

You can also stretch a net over your pond. These nets exist in all sizes.

More expensive systems exist. They are based on motion detection and trigger either flashes of light, or noise or water jets when herons or cats approach.

Finally, know that herons are afraid of glare. Thus, polished surfaces reflecting daylight can be enough to remove them. For example, place some decorative floating bowls in your pond to avoid them.

The installation steps

The preformed pond

  • 1. Clean the installation area of pebbles, tree stumps... to have a clear place

  • 2. Place the preformed tray in its place and mark its outline on the floor with a spray of paint and stakes. Remember to also materialise the different depth levels of your pond

  • 3. Dig the pit starting with the deepest parts. Provide a hole wider and deeper than the measurements of about 10 cm (4 in)

  • 4. Tamp the soil and smooth the surfaces. You can also add a sand bed at each level (then cover the bottom of the pond with about 10 cm or 4 inches of sand).

  • 5. Set up your preformed pond and check its level (using a spirit level) in several places. Adjust the level if necessary.

  • 6. Install the pond substrate if necessary (see "tools and consumables")

  • 7. Install the pump, filter, lamp and water / waterfall spray without connecting them

  • 8. Start filling the pond and check the levels again. Quick tip: raise your water meter before and after the end of the filling to know the exact volume of your pond! This will be useful if you have to use drugs, products of treatments or contributions of bacteria...

  • 9. Fill and stabilise the banks of the pond. Adjust well by filling in the empty parts between the pond and the pit. Check the levels again.

  • 10. Finish filling your pond

  • 11. Connect the technical devices and check their correct operation (except the lamps which will have to be connected at least 3 weeks after impoundment).

  • 12. Install the pond substrate on the edges of the pond

  • 13. Install your decoration. For example, you can dress the banks with gravel. Also install the plants and their baskets.

  • 14. Install your protective equipment (see “The safety of the pond" in "General advice")

The pond with tarpaulin

  • 1. Clean the installation area of pebbles, tree stumps... to have a clear place

    clear place for pond
  • 2. Make a paper diagram of your pond before you start

  • 3. Trace your pond on the ground with a spray of paint or materialize it with a long garden hose

  • 4. Dig your pit by creating 3 levels of depth:
    - The first floor at 10/30 cm (4 to 12 inch) to make your plantations and for the safety of your children and your animals. Plan a 45 degree slope to reach this depth.
    - The 2nd floor at 60 cm (24 inch) deep. This floor will cover 3/4 of the basin. Stay there on a slope of 45 degrees.
    - The 3rd floor at least 80 cm (32 inch) deep for small fish (example: goldenfish) and up to 200 cm (80 inch) for larger fish (koi carp).
    Do not forget that depth plays a big role. In cold regions, for example, a deep pond will prevent water from freezing and thus killing the fish and the plants. Similarly, in warmer regions, the water will stay cool in the depth.

    pond hole
  • 5. Tamp the soil and clean the banks

  • 6. Cover the soil with sand (about 5 to 6 cm or 1.9/2.4 in thick)

  • 7. Cover the sand with a geotextile fabric

  • 8. Install the tarpaulin (be careful, it can be quite heavy, plan to be at least two for this operation!). Unfold the tarpaulin from its center. To do this, locate the center of the sheet and arrange it in the axis of the basin (in the direction of the length). Then unroll it to the ends. Avoid a maximum of folds by smoothing the cover from the inside to the outside. The edges of the tarpaulins must overlap at the banks.

  • 9. Install the pond substrate if necessary (see "tools and consumables")

  • 10. Install the pump, filter, lamp and water / waterfall spray without plugging

  • 11. Start filling the pond slowly: take this step to smooth your tarpaulin and avoid larger folds. The remaining folds should flatten with the pressure of the water.

    pond hole

    Quick tip: raise your water meter before and after the end of filling to know the exact volume of your pond! This will be useful if you have to use drugs, products of treatments or contributions of bacteria...

  • 12. Connect the technical devices and check their correct operation (except the lamp which must be connected at least 3 weeks after impoundment).

  • 13. Dress your pond according to your taste with plants, decorations... Hide the excess tarpaulin with soil, pebbles and stones.

  • 14. Install your protective equipment (see “The safety of the pond" in "General advice")

Tools and consumables

Tools and consumables

  • A wheelbarrow to clear the earth from the pit

  • A spirit level

  • A shovel and a flat spade

  • A marking bomb

  • A meter

  • Sand

  • Pond substrate if needed (this choice will depend on the desired rendering.) For a "natural" pond with lots of plants, it is better to put soil at the bottom of the pond, but it will be more difficult to control the growth of the plants and the appearance of algae in this case. In contrast to a more streamlined basin, with a more decorative and controlled vegetation, so it’s better to have bins of plantation or plants in basket)

  • Pond pump

  • Pond filter

  • UV lamp

  • Pond protection

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