Instructions
Purchase your dead rock before you purchase your live rock, or at the same time. Living organisms on the live rock will begin to die quickly. This means you will either need a spare tank that has already been prepared, or be ready to set-up your main tank, as soon as it arrives.
Rinse off the dead rock under fresh water. You can use a sink or tub, or simply spray it with a hose outside.
Stack the dead rock in the bottom of the aquarium, using the largest pieces on the bottom of the pile. Leave lots of gaps and holes where fish can take cover and hide. Use your imagination, but be careful not to place the rocks where they may shift and crush the tank inhabitants or crack the tank.
Add the live rock, once you are satisfied with the arrangement of the dead rock. It's not unusual for aquarium owners to try several configurations before coming up with an arrangement they are satisfied with.
How to Use Dead Rock for a Saltwater Aquarium
Dead rock is also known as base rock, and it forms the backbone of many reef aquariums. Live rock is limestone rock that has been taken directly from a coral reef -- or from another aquarium -- and is still covered with all sorts of algae and marine life. Dead rock is simply live rock that no longer has any living organisms on it. It's not as pretty as live rock, but it is much cheaper. This makes it perfect for building up rock walls in areas that won't be seen.