Live Rock

What is live rock and how is it formed?

"Live rock" can be one of the most valuable elements in a marine reef aquarium as not only is it used as a building material for an aquarist's reef, but it can also play a substantial part in the biological filtration of the aquarium and add interesting organisms to the tank throughout its life.

"Live rock" or bio-rock is a natural by-product of erosion processes around coral and limestone reefs. Chunks of rubble rock, colonised by many types of micro and macro organisms, fall onto the seabed, often during tropical storms.

How is it collected and shipped?

Divers collect the rock from various depths of water, depending on the type of rock and diversity of life that is required, and then the rock is shipped as quickly as possible to the wholesaler.

The rock is always shipped without water in cardboard boxes with plastic liners so as to preserve as much moisture as possible. There are two main reasons for shipping the rock without water: firstly, the type of life that good "live rock" should support will not be significantly affected by shipping dry, and secondly, if the rock was shipped submerged in water the freight costs added to the cost of the rock would make it too expensive for the majority of aquarists to buy.

What should I look for when buying "live rock"?

For "live rock" to be biologically beneficial to the aquarium, it needs to be highly porous, allowing water to percolate deep into the rock's core. This means that the rock should be relatively light for its size. Low oxygen levels deep within the rock allow de-nitrification to take place, which will help to prevent the build up of nitrates in the aquarium, which is probably the most important feature of "live rock".

The rock should also have a good covering of coralline (pink encrusting) algae which, as well as having aesthetic benefits can also contribute to improving the water quality. However, it should not be covered in large numbers of polyps, sponges, soft corals or macro algaes. These will decay during shipping and when they are added to the aquarium can cause water pollution and damage to the biological balance in the aquarium. Before placing the rock in the tank, the rock should be examined carefully and cleaned of any excess decaying matter. It may also be necessary to "seed" large amounts of rock in a separate system to allow cleaning and re-colonisation of bacteria to take place, before adding the rocks to an established system.

What can I expect from "live rock" in my aquarium?

Once established, "live rock" can be used as the sole means of biological filtration in a reef aquarium. These new, natural methods of reef keeping rely on very few mechanical devices to look after the aquarium environment, perhaps only using a protein skimmer and mechanical filtration system to help with water quality management. These methods are gaining great popularity and can be very successful if used correctly.

Over a period of time the "live rock" will change and develop with the pink encrusting algae spreading over the rocks and rocks joining together. New algae and organisms will continue to appear giving the aquarist a continuously evolving eco system.

What rock is available from Tropical Marine Centre?

Tropical Marine Centre can supply two types of rock, both of which fulfil all of the criteria above.

Premium Grade Rock

This type of rock comes from various sources around the world and offers very good value for money. The rock comes in an assortment of shapes and sizes and is well known for its excellent biological capacity.

Caribbean Rock

This variety of rock is sourced from an experienced supplier in the Caribbean. It comes in particularly attractive shapes, most of which tend to be flatter than other types of rock. This often makes it an easy rock to build reefs with. It also has particularly good coverage of pink corralline algae and produces significant amounts of animal and plant life over time.

"All Tropical Marine Centre rock is guaranteed to have been collected using ecologically sound methods by responsible collectors."

For further information on this subject please read "The Modern Coral Reef Aquarium Volume 1" by Svein A Fossa and Alf Jacob Nilsen, which is published by Birgit Schmettkamp Verlag (1996) and distributed by TMC in the UK. For more information please call or e-mail us at sales@fishnthings.com