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905-715-2447 Winter Hours: By Appointment Only 3301 Sideroad 10, Bradford, ON Canada

Pond Filtration Basics

Pond Filtration Basics

Pond filtration basics. There are three main types of processes that occur in pond or aquarium  filters. Each type plays an important role in the overall filtration process and helps to provide a healthy ecosystem for fish and other inhabitants of the pond.

Pond Filtration Basics

The 3 Types of Pond Filtration Are:

  1. Mechanical
  2. Chemical
  3. Biological


MECHANICAL filtration is the most basic type of filtration. It involves removing suspended particles out of the water. This is usually accomplished with the use of filter media such as foam or filter matting, which trap debris. Regular cleaning of the filter media will help to keep the water free from floating particles

CHEMICAL filtration removes impurities from the water by chemical means. The most common type of chemical media used is activated carbon or charcoal. These remove colours, odours, ammonia and other organic wastes from the water by the process of adsorption. They are effective for a relatively short time and must be replaced regularly.

BIOLOGICAL filtration is the most important component in your filter for providing a clean healthy environment for fish. This involves a process called the NITROGEN CYCLE which relies on various beneficial bacteria to break down toxic waste products into less harmful substances. Simply explained, fish and decaying plants produce toxic AMMONIA, this is then converted by bacteria into NITRITES, and finally into less harmful NITRATES. Nitrates are then consumed by plants or algae in the pond.

An efficient filter should contain a filter medium that provides a large surface area on which the bacteria can grow. Since these bacteria flourish in clean, well oxygenated water, a filter should have effective mechanical filtration or pre-filter to keep the biological filter media from being clogged with debris. Constantly rinsing debris from the biological filter media will also rinse away the bacteria and not allow the filter to mature properly. Many of the newer filters are designed so that the mechanical filter can be cleaned regularly without the need to clean the biological media.

Most pond keepers tend to under-size the filtration systems on their pond, yet this is the most important component of a pond, especially if there are fish in the pond.

To truly get the best pond filtration, to have clean, clear water and  have optimum water quality – over-size your filter. buy a filter that is bigger than recommended -you won’t be sorry that you did. A larger filter will provide more surface area for biological filtration, will need cleaning less often and result in healthier fish.