Pond skimmer filters allow for easy access to your pond pump while they skim the surface of the water. These pond skimmer filters also act as the first stage in a pond filtration system since they have a leaf trap and filter pads inside of them. Pond skimmer filters also hide the pump and plumbing from view, allowing you to create a wonderful natural-looking koi pond. If you are installing a new koi pond as part of a kit, the skimmer filter is an essential piece of pond equipment. A pond skimmer filter attached to the liner using small bolts and silicone.