Thanks for your comments on my draft, they are very helpful!
At least I did manage to keep the language understandable for everyone.

"Wayne Sallee" wrote in message
ink.net...
Is this the book report that you are giving to your first grade teacher?

Wayne Sallee
Wayne's Pets



Guayni; SAHS wrote on 12/22/2006 8:14 PM:
Nitrates in Sal****er Aquariums
By Jaime Rivera-Sierra, www.guayni.com





Belief it or not, Nitrogen (N) and Phosphorous (P) are
limiting nutrients in the oceans. This means that producers such as
diatoms and other algae can't produce more because of limited amounts of
these two elements. This is the way that the oceans had evolved over
millions of years. When there is an excess of N and P, the algae bloom
causing red or green tides. This phenomenon instead of being helpful to
the ocean's inhabitants results detrimental by disrupting the entire food
chain and the ocean's equilibrium. In open waters this should be avoided
at all costs.



On this paper I will discuss the effects of excess nitrogen
in sal****er aquariums in various forms.



Nitrogen in a sal****er aquarium is present in four different
forms. I have to emphasize that it enters your aquarium in the form of
food.



The most stable form of nitrogen in an aquarium is in the form of living
tissue. Every living organism incorporates nitrogen to each and every
cell for many reasons. The amount of nitrogen not needed for flesh is
excreted back to the water in the form of ammonia.



The ammonia enters the water column in the form of urine, feces or gills'
secretions. A high level of ammonia in an aquarium is toxic to fish and
disrupts the other life cycles of your aquarium's residents. Ammonia is
the most toxic and unstable of the four nitrogen forms.



Once Ammonia enters the water column either evaporates as
ammonia gas (NH4+) or gets recycled in the nitrogen cycle. This task is
performed by nitrifying bacteria that turns ammonia (NH3) to nitrites
(NO2). In the nitrite form, N stays unstable replacing oxygen in
breathing and affecting in many ways the metabolism of your fish.
Although not as unstable as ammonia, nitrites will deteriorate your
aquarium and can kill your fish if levels exceed a tolerable margin.
High levels of nitrites must be avoided.



The nitrifying bacteria continue to process
nitrogen-containing compounds turning nitrites to nitrates (NO3). At
this point nitrogen is at its lowest unstable condition becoming
accessible to plants. In the nitrate form, algae and other plants
reincorporate nitrogen into its tissue. In open waters, these plants are
eaten by consumers restarting the cycle again. On the other hand, in a
closed system as your aquarium, nitrates accumulate to detrimental
levels.



An excess accumulation of nitrates may cause some problems to your system
as it remains unstable. NO3 can't be reduced again by nitrifying
bacteria and has to be removed from the tank. There are different
methods to achieve this task. The most common procedure is known as a
"water change". Using this technique, aquarists remove water from the
tank and replace it with waters with low nitrates levels, thus diluting
the water column. This method is costly and tedious requiring periodical
water changes that may range from twice a year to twice a week and from
10% to 20% of the water column. Another good method of extracting
nitrates from the water is by harvesting plants that incorporated
nitrates to its tissue. Since under this conditions N is not a limiting
nutrient, plants will bloom and algae will cover your tank making it easy
to remove. The more plants you harvest, the less need for periodical
water changes. Each plant you extract contains nitrogen built into its
living tissue from the most available source, NO3.



In summary, nitrogen is an element that needs to be controlled in your
system. The nitrogen cycle works only one way. The nitrogen in your
system enters in the form of food, this food is taken by your fish and
the excess is redirected to the water column in the form of ammonia.
Nitrifying bacteria turns ammonia to nitrites and then to nitrates. Once
the nitrogen is in the form of nitrates the only way out is mechanical.
An aquarist has to make a decision to extract nitrates directly from the
water by means of water changes or by harvesting plants that utilized
nitrates as nutrient.



References;



Dakin, N. 2003. Complete Encyclopedia of the Sal****er Aquarium



Mitsch, W.J. and J.G. Gosselink. 2000. Wetlands 3rd Ed.



Rivera-Sierra, J. 1992. Impacto Ambiental Acumulativo Del Desarrollo
Costanero En El Sector Playita De Salinas, Puerto Rico