Extra ceramic media can be added to your Reef One aquarium. This will increase the area available for biological filtration and makes it easier to anchor plants into position. The ceramic media should not need to be replaced, but if you wish to change the media you should do so gradually, in stages, and not all at once. Changing the media gradually allows the existing filter bacteria to move across and colonise the new media from the old. The ceramic media houses the beneficial bacteria that activate the biological filtration. The media is an inert, man-made material that will not alter the water pH. Adding additional media will increase the surface area available for bacteria colonisation enhancing biological filtration. INSTRUCTIONS 1 Rinse contents in tap water. 2 Discard any media smaller than a pea. 3 Gently place media into the aquarium by hand. Once the aquarium has matured, never remove or clean media in tap water.