When it comes to pond soil, opinions about the right substrate differ widely. While some pond owners can get by without any soil at all, others swear by ready-made products from the trade. But these pond substrates also differ greatly from one another. It is not that difficult to produce a solid pond substrate yourself.

Abandonment of pond soil

Pond substrate is important for plants, fish and ultimately also for the water quality. Because the plants cannot grow on the pond liner alone. Above all, however, a good substrate is essential for pond biology. It provides food and shelter for many creatures. And last but not least, the substrate is the colonization area for countless bacteria that ensure good water quality.

  • gives the plants support
  • provides a habitat for bacteria
  • binds nutrients
  • protects the pond liner from harmful UV rays and injuries


When choosing the substrate, you should pay attention to various factors, because an unsuitable material not only leads to contamination in the water, but can also damage the pond liner. A good pond substrate should therefore have the following properties:

  • low in nutrients
  • low in pollutants
  • smooth surface (never sharp-edged)
  • larger pebbles can also easily damage the foil
  • must not rot
  • difficult to wash out
  • must not float
Note: Do not use humus potting soil! Not only does it release large amounts of unwanted fertilizer into the water, which leads to an algal bloom, but it may also produce septic gases as it rots.


Unlike regular plants that grow on land, aquatic plants of any kind generally do not require humus rich soil to thrive. They get their nutrients from the water that washes around the roots. However, these plants cannot do without any substrate at all. Various materials are generally suitable as a pond substrate. Although they can also be used individually, in most cases a mixture of the different substrates makes sense in order to achieve an ideal result.

1. Choose

Coarse pebbles can damage the pond liner. For this reason, they should only be used in the bank area for design purposes. Fine gravel, on the other hand, is definitely a good plant substrate, as it provides support for the roots of aquatic plants and does not release any nutrients into the water. Although gravel itself cannot store nutrients from the water, over time the interstices fill with sediments that have sufficient amounts of nutrients.

2. Clay

Clay, loess or silt binds the nutrients from the water particularly well and is therefore an excellent substrate for aquatic plants in a garden pond. Even a small proportion is sufficient for the nutrient supply of aquatic plants. Clay is also not easily washed away.

3. Sand

The bacteria can settle very well in sandy substrates. As a breeding ground for the garden pond, sand is therefore ideal for stimulating plant growth and keeping the water clean. In addition, sludge does not accumulate between the individual grains, as is the case with gravel over time. Not only beneficial bacteria are present in this mud, but also pathogens and fungi that are harmful to the health of the fish can settle there. As a substrate, especially for fish ponds, sand is always the better alternative to keep the pond clean and the fish population healthy.

  • fine-grained sand for ponds without fish
  • do not use sharp-edged sand (e.g. sandbox sand)
  • river sand or aquarium sand is more suitable
  • coarse-grained sand for fish ponds

4. Lava granules or granulated clay

The porous material made of lava rock or clay offers ideal conditions for bacterial growth, which plays an important role in pond health. However, only use granules with a smooth surface, otherwise the foil, roots of aquatic plants or even the fish could be injured.

Tip: All the materials mentioned above can also be used individually as a pond substrate. Many pond owners have had good experiences with it.

purpose of use

In principle, the choice of a suitable pond substrate depends on where it is to be used in the pond.

Substrate on the pond floor – sub-substrate

The basis for a clear, healthy pond is primarily the substrate and bacteria. A good soil substrate should have a large surface area. The microorganisms that ensure clean and clear pond water need a substrate on which they can grow. All substrates that are very porous and therefore have a large internal surface are particularly good. Because that offers the microorganisms ideal growth and living conditions. And these microorganisms are important for a stable biological balance. For this reason, you should lay out around 60 to 70 percent of the pond liner with this bottom material.

  • purely mineral
  • must not have any sharp edges
  • Choose (Flusskies wie Rheinkies)
  • sand (river sand or aquarium sand)
  • Clay granules or lava granules in spherical form (quite expensive for large ponds)

Pond soil for the plants – grafting substrates

Marsh plants like the water lily do not thrive particularly well in a bed of pure sand or gravel. You need an adapted substrate with storage capacity for nutrients and a loose structure to ensure good circulation in the water and high oxygen levels in the root area.

Instructions for a solid pond soil

A pond soil for the plant baskets is very easy to make yourself. For a pond substrate that you can use for all types of plants, mix:

  • 10 parts clay minerals (clay, loess)
  • 10 parts sand or fine gravel
  • 5 parts clay or lava granules
  • 1 part rock flour
Tip: This pond substrate is not only lean and can store the nutrients well, it also largely avoids sludge.

A solid pond substrate should be purely mineral and must not contain humic soil. Fine gravel, sand or porous clay granules are suitable for the substrate. If you want to use plants, it is best to use a mixture of these components with clay in order to be able to bind the nutrients better.

Similar Posts

Leave a Reply

Your email address will not be published. Required fields are marked *