Preformed pond

A preformed pond or pond container is a plastic container, usually made of HDPE (High Density Poly Ethylene), in the shape of a pond. These preformed ponds have become very popular in recent years, and for good reason. They offer many advantages; for example, they are strong, durable, UV- and ozone-resistant, have a relatively low weight, and they can be purchased in many different shapes: square, rectangular, round, oval, L-shape or your own design. An additional advantage, pre-formed ponds have a ready-made profile with different depths for aquatic plants.

Construction of a preformed pond

Below we provide a brief description for constructing a pre-formed pond:

• Dig a pond pit that is around 10 cm deeper and wider than the depth and width of the pre-formed pond. Apply a good 10 cm of blowing sand or sheet sand to the bottom of the pit so that the pond after placement protrudes slightly above the pit. After filling with water, the pond container will sink slightly into the sand due to its weight.
• Place the container in the center of the hole, so that there is equal clearance all around the pond. Make the pre-formed pond level, by sliding a beam with a level on it back and forth over the edge of the pond container. Do this in all directions, the top edge of the pond must be exactly level. Otherwise, when filling the pond, one side will already overflow while the other side is still under the edge and the pond wall is visible.
• Apply a 10-15 cm layer of pond substrate or pond soil to the bottom of the pre-formed pond. This is important for aquatic plants and for the development and housing of beneficial bacteria. Never use ordinary garden soil or potting soil! This soil is far too rich in nutrients and will encourage the formation of algae.
• Fill the space between the pre-formed pond and the pond pit with blowing sand. Make it easy on yourself by making a thick porridge out of the blowing sand and water and pouring it into the gap. Fill the gap in several small increments. At the same time, let clean tap water flow into the pond to about the same height as you filled the gap with sand. This will prevent stress and damage in the preformed pond.
• When the pond is about 1/3 full, check again that the top edge is level. Now you can correct the pond if necessary. Now place the pond plants in the pond.
• Continue filling sand and water to about 20 cm below the rim. Let the pond rest for a few days to allow it to set. If it appears that the pond is no longer completely level, it is best to camouflage the crooked edge with plants.
• After a few days, refill the blowing sand to about 20 cm below the edge. Then top it up with regular garden soil for the plants around the pond. Finally top up the water to the desired level.
• Finish the edge with plants and other pond edging.

Biological balance

The construction of the pond is now complete. However, the new pond needs time to reach a natural biological balance. The water quality is not optimal right now. Pond plants and beneficial bacteria need to grow first. Therefore, wait before releasing fish. This process can be accelerated with different products. Before stocking fish, always measure the water quality.