Using dry rock in place of live rock has become increasingly popular among aquarium hobbyists, especially those who really want to control the content of their tanks. But the dry rock has zero ability to serve as a natural filter, unlike live rock which has bacteria living in the cracks and crevices. Additionally, the live rock is colorful and full of other beneficial and desirable life forms that dry rock just doesn’t have. Simply filling a new aquarium with dry rock will almost get you nowhere. Sure, the invasive algae and decaying life forms aren’t fouling up the water, but calcareous algae (e.g. coralline) is also lacking and it must be introduced. To seed the new rock, place some live rock from an established aquarium into your new aquarium. The animals and plants living on the live rock will spread onto the dry rock, making it live once again. This process does take some time, but in the long run your aquarium will have all of the beneficial life without the invasive kind.