Pondmaster Pads, Foam & Media
The media that you place in your filter servers different functions. The foam mats and pads strain out larger debris before it settles on the bottom of your pond or water feature. Lava rocks and biospheres/balls, or bio-matrix media provide a house for beneficial bacteria, that break down and remove organic material that otherwise would build up a sludge layer in your pond. You should make sure that the media in your filters are in good condition in order for them to work optimally.