Sand filter for the pond

Sand filters have excellent filter properties. Although they are known to many, especially by swimming pools, they show their strengths in applications such as the pond. The benefits of using a pond for a sand filter and how it is implemented are shown in the following guide.

Sand filter and filter with sand

First of all a distinction: there are sand filters with which sand is filtered out of a fluid, but also filters with sand as filter medium, which are called sand filters. The following guide applies to these. So it's about a sand filter system, which is operated in connection with a garden pond.

Sand filters are suitable for every kind of garden pond

It does not matter if it is a simple biotope for plants and frogs or maybe even a koi pond. The sand filter is basically suitable for any type of pond. An important effect that the sand filter brings for a pond is exceptionally clear water. Because many pond owners know only too well that the pond water is usually cloudy.

The peculiarities of many ponds

This is mainly due to the conditions that a pond brings with it. It is a stagnant water, which is usually also flat. Thus, the pond water heats up very much. Together with the nutrients associated with the rotting of pond plants, a pond is a near perfect location for algae. The strong algae blooms it is also, which provides in most cases for the greenish cloudy water.

Construction of sand filter system

The sand filter is a filter that initially works mechanically. To better understand the working principle of the sand filter system, first the construction. The sand filter system consists of the following components:

  • pump
  • manometer
  • filter housing
  • multi-way valve
  • Water supply system

Construction of sand filter

The filter housing is constructed from top to bottom as follows:

  • water distributor
  • one or more layers of sand
  • Filter star or filter cross
  • a standpipe that stands between water distributor and filter star in the sand
  • two outlets to the multiway valve

Operation of the sand filter system

The pond water is pumped by the pump via the multi-way valve via the water distributor in the filter housing. The water distributor ensures that the water is evenly distributed on the sand surface. Then the water seeps through the sand and reaches the filter star or filter cross.

At the end of the horizontal star or cross-diverging lines are pins or candles with punctual openings or slots. They are so determined in their size that only the water can enter. Now the filtered water is transported back to the pond.

Differences and special features compared to other filter systems

Conventional filters are concerned with the fact that the filter surface must be as large as possible, because the dirt particles are held on this surface. With a sand filter, however, it is more important that the water seeps through a high layer of sand.

Bacterial and mechanical water filter

At the same time, an anaerobic area is created, ie an oxygen-free zone. Therein, corresponding bacteria settle over time. Especially in a pond with fish, as in the Koi pond, there is an enormous accumulation of nitrogen.

In turn, it promotes algae growth. However, the bacteria in the anaerobic zone decompose the nitrogen. With a professionally constructed sand filter, this effectively filters both mechanically and bacterially. The result is crystal clear water for the pond.

Tips & Tricks

If you opt for a sand filter system, you can either purchase it commercially or build a sand filter yourself. However, construction and materials of sand filter systems are also crucial. As well as the various maintenance work, including the backwashing of the sand filter system.

Video Board: Koi Pond Sand Filter – Ask T.P.D. #31