A vegetable filter is a welcome addition to any water garden, as it provides a natural biofiltration mechanism above and beyond any other filter systems already employed. The concept behind a vegetable filter is that you simply pump water through the root system of aquatic plants, allowing them to absorb nutrients from the water and thereby assist in purifying the water. Below are pictures of the construction of a veggie filter that sits atop the pond it is helping to keep clean.
In these photos, you see the veggie filter come together as the sand bottom is put into place, followed by protective felt, a leveled top, a pond liner, and plumbing for the pump outlets.
If you'd like to learn more about water gardening, contact my friends at Green and Hagstrom through their Web site at Green & Hagstrom Aquatic Nursery and Water Garden Supply