The Filter Pro Green Coarse Filter Media is custom designed for use in ponds and other outdoor water garden applications. It can be cut to any size for your pond skimmer box or other filtration applications. The custom fiber weave design filters out unwanted debris for crystal clear water and provides an immense surface area which is ideal for beneficial nitrifying bacteria. Our Green Coarse Filter Media is tough enough to handle heavy debris like sticks and leaves, while still providing a high flow-rate required for oxygenating the large volume of water flowing through the filter systems or skimmer for your ornamental pond. This means healthy pond water conditions, and healthy aquatic plants and koi! This filter media is extremely durable and is also reusable. It can easily be rinsed out with a garden hose and reused many times. Made in USA.