The color of the water is caused by the presence of particles of organic matter decomposition results, metalalam ions (iron and manganese), plankton, humus, industrial waste, and water plants. The presence of iron oxide causes the water reddish, whereas manganese oxide causes the water brownish or blackish. The iron content of 0.3 mg / l and manganese content in increments of 0.05 mg / l is enough to cause the color of the waters (Peavy et al., 1985 in Effendi, 2003).
Calcium carbonate derived from chalky area cause a greenish tint to the water. Organic materials, such as tannins, lignin, and acid humus derived from the decomposition of dead plants that have lead to a brownish color. In the cultivation environment water color is also found to vary, among other things influenced by the content of the plankton in the water tergandung both phytoplankton and zooplankton, suspended solution, decomposition of organic matter, minerals and other substances that are dissolved in water.
The color of the water caused by the dominance of plankton can affect the color of the water, thus indirectly from the color of the water can also describe fertility waters. the color of the water caused by the dominance of plankton, among others:
a) Green, caused by Dunaleilla and Chlorella is a natural food which is good for biota farming, but there is also dominated by the green color and Enteromorpha are memeiliki Chaetomorpha unfavorable effect on biota farming.
b) Dark green, caused by the dominance Mycrocystis, Spirulina, Oscillatoria and Phormidium which include blue green algae. This plankton indicates the amount of organic material in the water such as ammonia and hydrogen sulfide, so that the waters with this color is not good for aquaculture activities aquatic biota.
c) Yellow brown, caused by Chaetocheros, Nitzchia, Gyrossigma and Skletonema or which include diatoms. diatoms will grow rapidly at a low temperature environment.
d) Green-brown, because the content Bacillariophyta, the color of the water is good for area farms because it indicates the amount of phytoplankton that can be used directly by zooplankton
e) reddish brown, they are due karean Peridinium and Schizothrix calcicolla or of the type Phytoflagellata most dangerous because of toxic plankton may issue endotoxins harmful biota farming.
Inorganic materials are also frequently provide certain colors such as calcium carbonate give a greenish color, can give green sulfur and iron oxides give color merah.Ada several colors of natural water for several reasons:
a) In general, ocean blue, this is caused by short-wave sunlight (blue light) reflected more than in any other light.
b) The color yellow, because basically there are yellow mud, for example, the Yellow River in China.
c) The green color, because of the mud that is deposited near the shore which reflects the green color and also because of the plankton in large quantities.
d) The color white, because the surface is always covered in sea ice as north and south poles.
e) The color purple, because of the small organisms that emit rays like at sea Ambon phosphorus.
f) The black color, because basically there are black mud as in the Black Sea
g) The color red, because of the many small animals red adrift.