Advanced Landscape Systems

Pond Filtration Types

The Basics

The key to having a well running pond is to have a well running filtration system. First, observe the pond filtration system and how it works.  Then identify problem areas, if any. While the water takes the path of least resistance see if it finds its way around the filter material and recirculates without being filtered.  If this is happening, the filter is stressed i.e. clogged up with gunk.  It is time to clean your filter.  If a filter is doing its job it will remove sediment from the water and the water flow will pass through the filter rather than around it. 

Filter Applications

Pond filtration can be done in different ways depending upon the application.  The standard type of filtration currently on the market is mechanical filtration.  This type of filtration uses media such as poly fiber, smart silk, netting, bead, or another type collector material to catch the debris.  Sediment loads can be heavy in the filter media.  It is important to have the right capacity filtration system to match the filter load of a pond.  This is determined size of the pond. 

Mechanical Filtration

Mechanical filters are typically the simplest of the common types of filtration systems. The basic concept of a mechanical filter is to remove the larger particles from the water. Water is usually drawn from the pond into a filtration tank, passing through various materials such as medium size gravel, plastic meshing or brushes which removes the particles from the water before returning to the pond. Mechanical filtration is often used in conjunction with other forms of filtration systems to produce a more efficient filtration system and clearer water requirements. Combinations include mechanical / chemical or mechanical / biological systems.

Chemical Filtration

Chemical filters change the nature of the harmful chemicals found in the water. Chemical filtration converts ammonia waste compounds into inert chemicals which are not dangerous to the fish. Activated carbon / charcoal and zeolite are the most popular examples of chemical filtration mediums. Both of these mediums have an excellent surface area that can act as both mechanical and chemical filters because of their porous nature.

Biological Filtration

Biological Filtration converts ammonium compounds to nitrates, which are relatively harmless to the fish. Such a filtration system may be incorporated within the pond during construction in the form of an under gravel filter or may be constructed externally in filter chambers containing a suitable medium. Certain bacteria which do not require oxygen derive their energy by breaking down organic matter. During this process, they release ammonia or ammonium compounds. These compounds in excess will kill fish and can accumulate very quickly if not filtered. Beneficial bacteria also exists within the pond environment.  Beneficial bacteria converts dangerous compounds into nitrates.  This beneficial bacteria colonizes inside the biological filter media and this is the reason why they are used in conjunction with various other filtration methods.

Under Gravel Filtration

Under gravel filtration is a form of biological filtration and is laid on the base of the fish pond. Under gravel filters cover the base of the pond and have the advantage that they cannot be seen. This type of filtration system consists of a network of pipes which contain a number of holes, through which water is drawn via a pump. As the water is drawn into the pipes it is passed down through a layer of gravel which is placed on top of the network of pipes. Providing the top layer of gravel is porous it will provide an excellent medium for bacteria to colonize and break down ammonia/ammonium compounds.

Plant Filtration

Plant filters act like biological filters as they remove nitrates from the water and are usually incorporated into the water circulation system. They can be included at various locations such as ponds at the base of a waterfall. Good water plants to use are water hyacinth, water iris and the hardy water lily just to name a few. Plants must be healthy so their roots can withstand the movement of water.

            Hardy Water Lily                                Iris                               Water Lettuce                                 Lotus