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I think, therefore I harm

Live Rock

For the sake of clarifying the title, please note that this post is categorized under Aquariums, not Music.

Despite its misleading name, live rock is not alive. The name comes from the many organisms that live on or in the rock. Live rock is used as the primary biological filtration in saltwater aquariums.

Real Fiji reef live rock, with its characteristic purple coralline

Real Fiji reef live rock, with its characteristic purple coralline

Live rock is usually dead corals. The hard, spongious skeleton from dead corals is an ideal home to a wide range of bacteria, algae and small organisms, all beneficial to the health of the tank. Mechanical or chemical filters are usually combined with live rock.

Live rock is often covered in coralline algae, a hard algae that doesn’t look alive, but which is important to corals. Coralline most often ranges in colors from pink, to red, to purple, but may also be pretty much any color such as yellow, blue or green. Coralline may make live rock look beautiful. Live rock is thus usually an integral part of an aquascape, though some hobbyists prefer to hide it from view.

Live rock is commonly harvested directly from the sea, near coral reefs, in tropical countries such as Fiji, Tonga and the Marshall Islands (all west of Australia), Bali (northwest of Australia) and the Caribbean. Because of ecological concerns caused by excessive harvest, a ban on live rock harvest existed for a short period in late 2008, but was later lifted. The short ban raised awareness though and an important part of the live rock offering is now from alternative methods.

Base rock

Another term widely used in the marine aquarium hobby is base rock. Base rock consists of rock containing no life. This is usually obtained by washing and bleaching regular live rock. The term is almost exclusively used for natural dead corals.


Base rock

Base rock is usually sold for slightly less than live rock, because it can be easily stored in a dry area rather than requiring maintenance in a water tank. It is not much less expensive though, as it is quite in demand by many hobbyists who prefer to keep control over what goes in their tanks.

Base rock is usually placed in an aquarium with an existing stock of live rock, or often in a separate water container with a small amount of live rock. In time, the live rock will seed the base rock, which will become alive once again.

DIY live rock

Do It Yourself live rock has been created by some hobbyists since the dawn of saltwater aquariums, mainly because of the excessive price of live rock. In the later years, it has also been popular with people looking for environmentally friendly alternatives.

A popular method is to mix cement with oyster shells, and some other materials which varies with creativity. An advantage of the method, beside its low cost, is that the rocks can be molded in any desired shape, including natural-looking ones.

The drawback is that it takes an extremely long time to prepare. The rocks need to be soaked in water (large containers such as small children pools are often used), with a lot of water movement, over a period that can easily reach six months. This is required to remove all dust from the rocks, and ensure that the rocks don’t change any water parameter anymore.

Aquacultured Fiji artificial live rock

While most people agree that alternatives to natural harvested live rock are desirable, it took a while to find a good one. In the late 1990s, when the saltwater aquarium hobby began, the harvest of live rock from the bottom of the sea was already a concern. Florida (as far as I am aware, the only American state with a coral reef) was quick on banning the process, and alternatives had to be developed quickly. Early methods were not very efficient and were often more expensive than importing live rocks.

Fiji was among the first few countries to develop an industry around the harvest of live rock. Already in 2001, concern was raised there regarding excessive harvesting. Finding Nemo (2003) created a sudden keen interest in the hobby and increased the demand for live rock. Prompted by the concern, one of the companies there tried a new method in 2004. They used pumice, a porous volcanic rock commonly found on the shore of Fiji, and cemented into doughnut shaped rocks. They strung the rocks with a cable which they anchored to the reef. Eight months there and the rocks are turned into new, artificial live rock. The first test was successful, though it wouldn’t be enough to supplant the income of a full-time harvest.


Walt Smith’s Fiji Cultured Live Rock

Opening in late 2005, the Georgia Aquarium purchased all 50 metric tons of the new live rock produced the first year, which it needed for its coral tank. The product is now available on the market worldwide under the name of Walt Smith’s Cultured Fiji live rock. It is generally sold for slightly less than natural live rock from the same origin.

Other companies now sell very efficient synthetic live rock, made from different materials, which differ in appearance. Some of these look very natural. They are usually priced lower than natural live rock, but not always. They are in demand by hobbyists looking for greener, but also safer alternatives to sea seeded live rock, as rock seeded under controlled conditions are less likely to hold any undesirable organism.

Once considered among the best quality, the Fiji live rock is now ranked second by many hobbyists, which are now looking into rock from other sources. It would seem that all the good rock was already harvested. Many have turned to Bali live rocks. Synthetic live rock has not yet received wide attention and natural live rock, which is for most purpose eternal, is being resold among hobbyists, often for prices which equal or exceed the original ones as these rocks, when well maintained, age like old wine, hosting a better quality, well controlled life.

This is my new saltwater tank being cycled with all the basic equipment. At the bottom lies $200 worth of cured live rock.

This is my new saltwater tank being cycled with all the basic equipment. At the bottom lies $200 worth of cured live rock.


One comment on “Live Rock

  1. Mohan Priyanath
    February 16, 2015

    i have a problem when numbering these rocks,we generaly number this rocks in a cement surface,but when we harvest after 3,4 months that number is covered with algae,as we depositing 1000+rock at ones its unable to use laminated tags also(they can damage) so have you got ant option to avoid this,i mean some kind of chemical which we can apply ONLY to that numbering cement ring to avoid algae growh

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This entry was posted on April 17, 2014 by in Aquariums and tagged , , , , , .
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