What is 'Black Water' and why are they used in Arowana tanks?

There has been many questions posted about why Arowana hobbyists are using black water with their tank water..  I have provided an excerpt of an article I wrote recently which is published in a few article directories.  

" Arowanas natively inhabit black water rivers and wetland areas.  Black water is incredibly clean and tends to support a wide variety of unique fish species specially adapted to its attributes.

Black water is acidic, soft water fed by black water streams originating from ancient tropical forest soils that are low in nutrients.  The lack of minerals present in these soils keeps black water soft.  The decaying leaves of Ketapang Trees that fall into black water release tannins and humic acids which further soften it. These organic acids dye the water a distinctive tea color. 

The brownish-yellow color of black water is believed to contribute to the bright,iridescent colors typical of many black water fish species, including Arowanas.  Vibrant coloration may make it easier for species to spot each other in darkly colored water. 

Many hobbyists and professional breeders prefer to reproduce black water conditions in their Arowana aquariums.  Dried Ketapang leaves are used to promote a healthy environment, induce spawning, and lower the pH of tank water. The natural organic acids released by the leaves may help absorb undesirable chemicals, detoxify the tank, and reduce the population of undesirable bacteria.

Peat and decayed driftwood are two other black water additives used in Arowana  tanks.  Commercially prepared “black water extract” is another option.  When  creating black water conditions, care should be taken that the tank’s pH does not become too acidic or dip below 6.5 – 7.0.  "

If you want the full article, you can check it out at http://ezinearticles.com/?The-Natural-Approach-to-Asian-Arowana-Care-in-Captivity&id=415247