Keeping Your Pond Filtered from Bacteria & Debris
A pond filter is required to clean and filter the pond's water. If the pond contains any fish, such as Koi or goldfish, more filtration will be required.
A combination of mechanical and biological pond filtration makes for a good pond filter. Biological pond filtration breaks down fish waste and organic matter using beneficial bacteria. Mechanical filtration captures particles in a physical filter for removal during the pond's cleaning. A good pond filter should be able to achieve both and should also be compatible with UV clarifiers for algae control.
An out-of-pond filter allows easier convenience for cleaning and maintenance on your pond. Depending on your choice of filter, some must be installed specifically at the highest point of water discharge. Other filters, like pressurized pond filters, can be installed at any level because the force of the water exiting the filter is equal to the force of water going in. Essentially, this gives you two options for pond filters, submersible and biological.
Lava rock filter systems are advantageous for fish ponds. The porous lava rock gets covered with the good type of bacteria and breaks down ammonia. You need to use quite a lot of lava rock for it to work properly. You can make your own out of a large drum. You can also use barbecue lava rock, but look for the largest rocks you can find so it's easier to clean.
Many pond filters come with the recommended pump as a package, but filters can also be purchased singly. Your garden pond filter should filter half the pond volume every hour at a minimum. Garden ponds that are exposed to the sun for more than 6 hours a day, and Koi ponds, should have a slightly larger filter. A prefilter is also a requirement which is installed at the beginning of the water filter cycle.
Filters vary in price depending on the size and power you require. They usually range from $280 and $1000, depending on the water volume in gallons. But they can get up to $2,500 for ponds with up to 25,000 gallons of water.