There are a number of established ways to keep a garden pond clean. Which of these is suitable in each case depends on the size of the pond, the function of the pond and the ecological requirements of the owner. Here we take a close look at the filter ditch.

A filter ditch is mainly used for large ponds

The filter ditch as a natural filter chamber

First of all: The pond filter option of the filter ditch is only suitable for large plots of land. Depending on the function of the pond, the ditch must take up a significant proportion of the volume of the pond itself. The ditch must be particularly large for ponds that are particularly stressed by a lot of water movement and foreign bodies being washed in. These include above all:

  • Ponds with fish stocks
  • swimming ponds

With these pond types, the filter ditch should take up at least 20% of the pond size. In the case of fish ponds with a high stocking density, it is even advisable to make the filter ditch just as large as the pond itself.

How the filter trench works

A filter ditch is created near the pond and connected to it by an underground hose. Its task is to constantly flush the pond water in the sense of a filter pump system and then clean it and return it to the pond. That means: A circulation pump at the end of the ditch is usually still necessary. It transports the water from the ditch inlet to the outlet and back into the pond. The difference to the complete filter pump system: the water is cleaned by plants instead of the filter inserts.

The cleansing power of plants

A filter ditch must therefore be equipped with plant species that have a particularly high nutrient turnover. In addition to suspended matter, they should also break down amino acids, convert nitrate to nitrogen and release oxygen. Examples of plants that are good at this are:

  • calamus
  • Cattails
  • frog bite
  • crab claws
  • water star

If you use such purification plants in the filter ditch, you can plant your pond purely according to ornamental aspects.
In order to optimally shape the course of the clarification from coarse to fine, you should place reeds and floating leaf plants at the beginning of the ditch and finely branched underwater plants further back.

Shape and structure of the ditch

In order for the water flow to be as undisturbed as possible, the ditch should ideally be straight. Incidentally, this is also easier for building and laying out with foil. In the initial area, you should fill the trench with pebbles that are as lime-free as possible. So that the ditch disturbs as little as possible and does not take up so much usable space in the garden, it makes sense to create it on a long edge.

Category:

Garden design