KoiPondFever.com offers only the best pond filtration products whether you need a pond filters or a koi pond filters to help keep the water clean and free of algae. Decaying plant mater, windblown debris, and fish waste contribute to poor water quality and sometimes require extra filtration, both mechanical and biological. Unlike an aquarium where the water can be changed to keep the water parameters in check, the fish pond filter relies more on biological and mechanical filtration to keep things in balance. Especially in a koi only pond or a koi watergarden that has a heavy fish load, external pond filters provide the extra filtration needed. Garden pond filters do not have to work as hard as fish pond filters. As the pond matures and the koi grow and multiply the existing pond filter system is not enough to keep up with the fish population. Don't feel alone as many koi pond keepers end up adding to the koi pond filter system.