Bio-Rock is a technology that uses low voltage electrical current on artificial underwater structures to encourage the growth of corals and other reef life. First created by architect Wolf Hilbertz and Tom Goreau, experiments with the technology worldwide have shown that it can help counteract some of the difficult environmental factors affecting coral growth.

Otherwise known as Mineral Accretion technology, the low voltage electricity encourages some of the naturally occurring minerals that corals and other marine organisms use in abundance to fall out of the water and accumulate onto the structures. This helps corals by increasing the nutrients needed for growth resulting in coral growth up to 4 times faster than normal.  

In conjunction with Save Koh Tao, Big Blue Conservation and a consortium of other dive schools launched a pilot project a few years ago to see if the technology would be successful here. The pilot project has been so successful that a new larger Bio-Rock was constructed in 2008.

When the structure was first finished, test subjects were placed on the structure and tagged so that their growth could be monitored. This information is collated by Marine Conservation Koh Tao for scientific purposes. When a dive group visits the structure, various data including photographs are taken and then forwarded to Marine Conservation Koh Tao.

Since the success of Hin Fai (Power Rock), Koh Tao now has a total of 2 more additional Bio Rock reef structures, located on the east side of the island; one in Aow Leuk bay deployed by the local conservation team at New Heaven, and the other deployed in Hin Wong Bay by Coral Garden and Big Blue Conservation.  The later was designed to use a more efficient and environmentally sustainable energy method; solar power. 

How does it work?

It uses a well-known process called electrolysis, which is also used for other applications such as plating metals, removing rust, creating hydrogen batteries, and more. During this process, low voltage, direct current is applied to two pieces of metal that are submerged in water. At one end of the circuit, called the Anode, electrons flow from the wire into the water and cause H2O to break-up and oxygen to form. The water surrounding this area becomes quite acidic, and therefore the anodes are kept small and suspended in the water. At the other end of the circuit, knowns as the Cathode, electrons flow back from the water into the metal, causing H2O to break up and release hydrogen bubbles into the water. At the Cathode, the surrounding water becomes quite alkaline, and in these conditions, calcium and other minerals are no longer soluble in the water and precipitate out to accumulate onto the metal. For coral restoration, corals and other organisms are planted on the cathode, which is usually made of steel rebar and can be shaped into any design imaginable.