Just as in a home aquarium, a Koi pond will also require of a filtration system in order to ensure a safe environment for your Koi fish. The main purpose of a Koi filter is to remove solids from the pond water and to help balance the nitrogen cycle of the pond.
Just like in home aquariums, there are three primary classifications of Koi pond filters. These are mechanical, biological and chemical.
Mechanical filters work by using a filtration medium, usually filter wool or a sponge, to capture solid material from the water. In the case of a Koi filter, most varieties on the market will combine the mechanical and biological elements of filtration in a combined unit or system. Chemical filtration in Koi ponds is normally used in conjunction with the addition of an added filtration medium consisting of activated carbon. This activated carbon assists in removing ammonia, heavy metals and other contaminants from the water.
Due to their size, a fourth type of filtration method is also increasingly used in Koi ponds. This particular type of koi pond filter is the UV filter. These devices employ ultraviolet radiation to kill fungi, algae and other pathogens in the water. As such, they are highly effective at eliminating algae from ponds as well as removing other organisms which could spread disease to your Koi fish population.
The following are some popular Koi filter categories:
Gravity Box Filters
This type of Koi pond filter is the most affordable to set up for a Koi pond. It uses a water pump to bring water to a container, or box, which should be placed at the highest point of your pond layout. From here the water passes through filtration media, mechanically removing solids and performing biological filtration by allowing colonies of beneficial ammonia oxidizing bacteria to live on the filter medium itself. The water returns to the pond with the sheer force of gravity.
A skimmer filter is a Koi filter that skims the water surface removing all solid debris from the surface before it sinks and collects at the bottom of the pond. Some of these perform a purely mechanical filtration function. Some upper tier models also combine a biological filtration function by passing the returning water through a filtration medium. Most skimmer filters are all inclusive units, combining the water pump into the unit casing itself.
Of all Koi pond filters, the waterfall filter combines functionality with the added benefit of contributing to the overall ambiance of your Koi pond. As its name implies, this type of Koi filter creates a waterfall effect as part of its filtration process. In most models, water is pulled into the unit from it base by means of a water pump. The water then travels upward, passing through a filter mat for mechanical filtration and filter media for biological filtration. The entire waterfall unit then acts as a weir to create a waterfall effect with the water as it is returned to the pond.
Not only does a waterfall filter add visual depth and character to your Koi pond, but it also helps in greatly enhancing oxygen absorption for the pond water by creating the cascading effect as it is returned.
A pressurized filter is a self-contained unit that houses the water pump as well as the mechanical and biological components of the filter unit in a self-contained apparatus that can be placed anywhere. In fact, most pressurized filtration units are installed away from the pond in order to facilitate cleaning and/or not to interfere with the aesthetics of the pond. It is with this type of koi filter in which UV filtration can also be added. The intake and return of water is handled via hoses.
As with home aquariums, the aquarist’s maxim of buying the best filter that you can afford holds true for Koi ponds as well. Find the filter that best suits your budget, size of fish population and that blends nicely with your overall look for the Koi pond. A reliable filter is the most important piece of equipment that you can buy to ensure that your fish live happy and healthy lives.