For a garden pond containing fish, you should consider purchasing a pond filter. The filter will keep your pond as enjoyable and rewarding as possible. Fish waste, algae and debris can clog the pump, make the water toxic for the fish or just make your pond unpleasant to look at and be around. A filter will help keep the pond clean and maintain the ecosystem within. There are several types of pond filters to discuss and hopefully this will help you make a wise purchase.
Mechanical filters use foam, brushes or gravel to strain the water and trap any solids that exist. The filter will need to be cleaned and maintained to assure that it is always working properly. Mechanical filters vary in size and method.
An intake filter is a small mechanical filter and has a main purpose of keeping large debris from reaching the pump. Although this is extremely helpful, it does not take care of the fish waste that could jeopardize the health of your pond. If you have fish, or plan on having fish, in your pond, this type may not be the best. They will generally fill with debris quickly and may require daily maintenance in summer months. Although the filter is small and requires quite a bit of maintenance, this type of filter is certainly better than no filter, if this is your only option.
A submersed filter can be attached to your pump and will serve both the pump and the water for keeping things clean. It uses different filtering media for different jobs which can be combined for individual pond needs. Such media include a coarse pad, a porous stone, and/or a chemical compound, all used for different types of waste and debris. The submersed filter usually can take care of more waste than the intake filter, and therefore does not need to be cleaned as often, though when it does need to be cleaned, you might have to wade into the pond, depending on filter location and pond size.
An in-line filter also attaches to the pump, and like the submersed filter, can combine filtering media. The in-line filter can operate outside of the pond, which makes it easier to maintain. An in-line filter is a sealed canister, which means it can be used in combination with the pump for extras like waterfalls and fountains. Some people find the canisters difficult to open during cleaning, so be sure to consult with a pond filter retailer for more information about the easiest in-line filters to clean and operate.
An external filter sits above ground or partially buried near the pond. The pond water enters the top of the filter, trickles down through a combination of filtering media and then re-enters the pond. This type of filter is best for ponds with several fish because it cleans the most efficiently. It is also much easier to clean as it does not have to be in the pond. But, it is larger and sits above ground, so it may not be as aesthetically pleasing as some other filters.
Biological filtration involves natural bacteria that grow on a filter medium. The bacteria convert ammonia and other fish wastes into harmless substances. But, keep in mind that it takes up to six weeks after installation for the bacteria colony to mature and really be able to do a good job cleaning the pond. Also, the filter must constantly be on for the bacteria to live. After 24 hours of the filter being off, the entire colony will die. These filters should only need to be cleaned once a season, but if you think it needs a cleaning mid-season, only use the pond water as chlorinated tap-water will also kill your bacteria colony. Filters combining biological and mechanical methods are sold and could really benefit a large and/or heavily populated pond.
Ultraviolet lights can be used to minimize algae growth in your pond. The light will kill the algae and make it clump together so that a mechanical filter will more easily catch it. The ultraviolet light will not remove any nutrients from your water, nor will it harm your fish. The ultraviolet light system is most beneficial when combined with a mechanical and/or biological filtration system.
In order to purchase the correct filter, you will need to calculate the volume of your pond. To do this, multiply the average length, width and depth of your pond. Multiply that amount by 1000 if you’ve measured in meters (this will give you volume in liters) or by 6.25 if you’ve measured in feet (this will give you volume in gallons).
