WATER, A HAVEN FOR LIFE

PEAT
Peat derives from the decomposition of vegetation in an acid environment lacking in oxygen.
This process, which lasts several centuries, gives rise to a peat bog from which compact,
fibrous peat can be extracted. It endows water with both a yellow amber color and acidity, which
gives it slightly antiseptic properties. This means that some diseases are less common in acid water. The use of horticultural peat, which often has been enriched with various products, must be avoided in
favor of the peat for aquarium use that is commercially available. Boil it for around 15 minutes before use.

In the Amazon region of South America, the color of the water anges from amber yellow to brown, due to the leaves and branches floating in it. In an aquarium, peat can be used in the filtering equipment to reproduce the characteristics of this type of water (low hardness, pH under 7, coloring).

TURBIDITY

The turbidity of water refers to the presence of suspended matter - either living organisms forming plankton (rare in an aquarium) or inert matter, such as animal or vegetable remains or particles of sediment,particularly mud.
The size of this suspended matter ranges from a few thousandths of a millimeter to
several millimeters. In calm, unstirred water it forms sediment at a speed in proportion
to its weight. In running or turbulent water, some of the matter remains
permanently suspended, giving rise to more pronounced turbidity.
In aquariums, where the water is always in motion, systems of varying degrees of
sophistication (see Filtration, page 237) allow fish keepers keep their water clear.
The effects of this are entirely positive:
- the visual appearance is improved;
- the light required by the plants penetrates the water and reaches them more easily;
- there is less risk of disease, particularly in the fishes' branchlike;
- there is little sedimentation on the base of the tank, reducing both the possibility
of any warping due to excessive weight
and the decomposition of organic matter

FRESH WATER FILTERS

This type of water is also known as Continental water, a more accurate term from the
scientific point of view. Continental water accounts for only 2.6% of the Earth's water, the
rest being made up of seas and oceans. Of this volume, 98% consists of sterile water, in the
form of glaciers and underground water, leaving only the water of rivers, lakes, and ponds
as shelter for living organisms- barely 2% of the total volume of Continental water

TEMPERATURE                                          
An important parameter for aquatic life,
the temperature regulates the growth of
animals and plants and exerts an influence
not only on oxygen levels but also on
many other factors.
Whereas mammals have a regulated and
practically stable internal temperature,
that of fish and other aquarium creatures
varies according to the temperature
of the water around them. They
can survive only at certain temperatures
and some species are more sensitive than
others to variations in this parameter.
The temperatures of fresh tropical waters,
ranging from 20 to 30°C, are characterized
by less significant variations than those
found in temperate regions. In some
places the shade provided by the tropical
forest cools the water, while in calm water
the temperature goes up under the direct
influence of the sunlight.
The mean temperature most often recommended
for aquariums is 25°C, and variations
of 1 or 2° are of little consequence.
Fish are even capable of withstanding
even more significant variations for brief
periods (under 24 hours). On the other
hand, their metabolism (i.e. their general
bodily functioning) is in danger of serious
disturbance over any longer periods, and

be noted that excessively low temperatures
sometimes favor the development of
certain diseases.

OXYGEN AND CARBON
DIOXIDE
Since air contains around 20% oxygen,
even the most oxygenated water rarely
contains more than 1% dissolved oxygen.
Fish have special organs - branchiae -
which allow them to extract most of this
(see Anatomy and Biology, page 42).
Oxygen contributes, in
addition, to the respiration
not only of
plants but also of
organisms which are
invisible to the naked
eye and often forgot

Biological filtration and the nitrogen cycle

Proper management of the nitrogen cycle is a vital element of a successful aquarium. Excretia and other decomposing organic matter produce ammonia which is highly toxic to fish. Bacterial processes oxidize this ammonia into the slightly less toxic nitrites, and these are in turn oxidized to form the much less toxic nitrates. In the natural environment these nitrates are subsequently taken up by plants as fertilizer and this does indeed happen to some extent in an aquarium planted with real plants.

An aquarium is, however, an imperfect microcosm of the natural world. Aquariums are usually much more densely stocked with fish than the natural environment. This increases the amount of ammonia produced in the relatively small volume of the aquarium. The bacteria responsible for breaking down the ammonia colonize the surface of any objects inside the aquarium. A biological filter is nothing more than a chemically inert porous sponge, which provides a greatly enlarged surface area on which these bacteria can develop. These bacterial colonies take several weeks to form, during which time the aquarium is vulnerable to a condition commonly known as "new tank syndrome" if stocked with fish too quickly.

Aquarium filters

Aquarium filters are critical components of both freshwater and marine aquaria.Aquarium filters remove physical and soluble chemical waste products from aquaria simplifying maintenance. Furthermore, aquarium filters are necessary to support life as aquaria are relatively small, closed volumes of water compared to the natural environment of most fish.

Public aquariam

Most public aquarium facilities feature a number of smaller aquarium, as well those too large for home aquarists. The largest tanks hold millions of gallons of water and can house large species, including sharks or beluga whales. Dolphinaria are specifically for dolphins. Aquatic and semi aquatic animals, including otters and penguins, may also be kept by public aquaria. Public aquaria may also be included in larger establishments such as a marine mammal park or a marine park.

Salt Water Aquarium

Aquarium may be grouped by their species selection. The community tank is the most common today, where several non-aggressive species live peacefully. In these aquaria, the fish, invertebrates, and plants probably do not originate from the same geographic region, but tolerate similar water conditions. Aggressive tanks, in contrast, house a limited number of species that can be aggressive toward other fish, or are able to withstand aggression well. Specimen tanks usually only house one fish species, along with plants, perhaps found in the fishes' natural environment and decorations simulating a natural ecosystem. This type is useful for fish that cannot coexist with other fish, such as the electric eel, as an extreme example. Some tanks of this sort are used simply to house adults for breeding.