There are several types of pond filters available today for the pond keeper to choose from. The filters can generally be broken down by where they are placed.
These represent the simplest design for pond filtration. Most submersible filters will consist of a filter box with mechanical filtration and some chemical filtration, like the Pond Master series. Larger units will also incorporate biological filtration media as in the Laguna Power Flo Filter. The Pond Master series includes a submersible water pump with fountainhead outlets. Generally, this filter system is for smaller ponds of less than 1,000 gallons. Sometimes, the submersed filter box is used as a pre-filter for a water pump used to run the second class of pond filters, which are external filters.
These filters are designed to be placed along the side of the pond. From there, external pond filters return the water to the pond via gravity flow. Most are designed to use a submersed water pump that pumps the water to the top of the filter container. The water then cascades through filter media, usually a mix of mechanical, chemical. and biological media. This basic design is the setup found in the ClearChoice Bio Filters. Recently, many of the external filters started to also incorporate an ultraviolet sterilizer/clarifier to help control free-floating algae. This is the design of the BioStar and Fish Mate U/V Bio Pond filters. These filters are designed for ponds from 1,000 to 5,000 gallons.
For larger ponds, consider the BioTec External filter, a large multi-chambered system with mechanical and biological filtration media. The large size and types of media used in these filters are easy to clean and replace, making filter maintenance a snap. Other options for larger ponds are the pressurized external filters like the Sand Filters and Pressurized UV+Bio filters. The Sand Filters will require a self-priming external pump rated from 1/6 to 1 horsepower. The UV+Bio filter can use a large submersible pump rated at 1,000 to 2,000 GPH.
This third class of filters represents the fastest growing segment of pond filters and is designed for ponds from 1,000 to 10,000 gallons. The basic design includes a filter body that is placed in ground next to the pond and uses a skimmer method to draw in water from the pond. The water then passes through a mechanical filter system that is designed to be easily cleaned or replaced. You use a submersible pump to return water to the pond through a discharge pipe. Often, these skimmer filters are used as a pre-filter to a large-scale external filter. This offers the combination of an easy-to-clean pre-filter and more filter capacity for any size pond.
With these tips, you should be able to choose the right pond filter and enjoy great filtration success.