Nitrogen cycle
Nitrogen cycle – Important steps
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Stage1 – Entry and Accumulation
Ammonia is introduced into the water via tropical fish waste, uneaten food, and
decomposition. These will break down into ammonia (NH3). Ammonia is harmful to
tropical fish.
Stage2 – Nitrification Part 1
Soon, bacteria called nitrosomonas will develop and they will oxidize the ammonia
essentially eliminating it. The byproduct of ammonia oxidation is Nitrites. So we no
longer have ammonia, but we now have another toxin to deal with - Nitrites. Nitrites
are just as toxic to tropical fish as ammonia.
Stage 3 – Nitrification Part 2
Bacteria called nitrobacter will develop and they will convert the nitrites into nitrates.
Nitrates are not as harmful to tropical fish as ammonia or nitrites, but nitrate is still
harmful in large amounts.
Stage 4 - Denitrification
Denitrifying bacteria can breakdown nitrates into harmless nitrogen gas that escapes
through the surface of the water.
Nitrogen cycle – Impact on oceans
• Human activities have a significant effect on
nitrogen cycling. Production and use of
nitrogen fertilizer, combustion of fossil fuels,
and planting crops that fix nitrogen have
unbalanced the previously stable relationship
between fixation and denitrification. Gaseous
industrial pollutants foul the air in many cities
and wash out in sufficient amounts to
constitute “acid rain” in some parts of the
industrialized world.
Nitrogen – Regulating in an aquarium
• For a short period of time, a new aquarium is a toxic
cesspool. The water may look clear, but don't be fooled.
It's loaded with toxins. Fortunately ,bacteria that are
capable of converting wastes to safer by-products begin
growing in the tank as soon as fish are added.
Unfortunately there aren't enough bacteria to eliminate
all the toxins immediately, so for a period of several weeks
to a month or more, your fish are at risk.
• Ways to cycle your tank:
1. Use fish food
2. Use substrate or filter media from an established tank
3. Use a liquid bacteria culture, such as Stress Zyme
Phosphorus Cycle
Phosphorus – Important Steps
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Stage 1 – Entry and accumulation
– Phosphorus is not highly soluble, binding tightly to molecules in soil, therefore it mostly
reaches waters by traveling with runoff soil particles
– Weathering is the breaking down of rocks, soils and minerals through direct contact with
the water
– Leaching is the loss of mineral and organic solutes due to percolation from soil
Stage 2 – Uptake
– Plants dissolve ionized forms of phosphate. Herbivores obtain phosphorus by eating
plants, and carnivores by eating herbivores. Herbivores and carnivores excrete
phosphorus as a waste product in urine and feces.
Stage 3 – Decomposition, Sedimentation, and Uplift
– Phosphorus is released back to the soil when plants or animal matter decomposes
– The final resting place for Phosphorus is in the ocean sedimentary beds, where it will
eventually return to use via uplifting of sedimentary rock.
Phosphorus – Impact on oceans
• Phosphorus is usually present in natural water as
phosphates.
• Phosphorus is a plant nutrient needed for growth and
a fundamental element in the metabolic reactions of
plants and animals (hence its use in fertilizers).
• Sources of phosphorus include human and animal
wastes (i.e., sewage), industrial wastes, soil erosion,
and fertilizers.
• Excess phosphorus causes extensive algal growth called
"blooms," which are a classic symptom of cultural
eutrophication and lead to decreased oxygen levels in
various bodies of water.
Phosphorus – Regulating in an
aquarium
• Fortunately phosphates do not directly harm your fish, even at high levels.
However, the algae blooms that result from elevated phosphates can
ultimately cause problems for the aquarium inhabitants. For instance,
green water can deplete the oxygen, which in turn can harm the fish.
• Techniques to regulating phosphorus levels:
1. Water Change – Large water changes will help bring phosphates
down quickly, but if the underlying sources are still there, it will only
be temporary
2. Tank Cleaning – Scrape the inside of the glass, remove the rocks
and other decorations and scrub them well
3. Phosphate Absorber – Phosphate absorbing media is very
effective. It can be added to virtually any filter. NOTE: Generally using
chemicals should be your last resort.
Carbon Cycle
Carbon – Important steps
Stage 1 – Entry and accumulation
Carbon dioxide enters the waters of the ocean by simple diffusion.
Stage 2 – Uptake
- Certain forms of sea life biologically fix bicarbonate with calcium (Ca+2) to
produce calcium carbonate (CaCO3). This substance is used to produce shells
and other body parts by organisms such as coral, clams, oysters.
- Marine plants in the sunlit surface layer of the ocean grab carbon dioxide
from the air to use in photosynthesis
- When the plants die, they sink as so-called “marine snow” to the deep ocean
where the carbon is stored and prevented from re-entering the atmosphere.
Stage 3
- At the surface of the oceans where the water becomes warmer, dissolved
carbon dioxide is released back into the atmosphere.
Carbon – Impact on oceans
• In the aquatic ecosystem carbon dioxide can be
stored in rocks and sediments. It will take a long time
before this carbon dioxide will be released, through
weathering of rocks or geologic processes that bring
sediment to the surface of water.
Carbon dioxide that is stored in water will be present
as either carbonate or bicarbonate ions. These ions
are an important part of natural buffers that prevent
the water from becoming too acidic or too basic.
When the sun warms up the water carbonate and
bicarbonate ions will be returned to the atmosphere
as carbon dioxide.
Carbon – Regulating in an aquarium
• Carbon is considered chemical filtration. The
effectiveness of activated carbon is based on a
three-step process.
– The first is adsorption. Static forces will attract
particles and bacteria adsorbing them onto the
surface of the carbon. Bacteria that settle on the
carbon surface will further consume the waste.
– Another process is the diffusion of gases. Absorbed
into the carbon, the gases are detoxified.
– The third process is called chemisorption, where
particles are irreversibly bound to the carbon and are
used to attract other toxins.
Water Cycle
Water – Important steps
• The major physical components of the global water cycle
include the evaporation from the ocean and land surfaces, the
transport of water vapor by the atmosphere, precipitation
onto the ocean and land surfaces, the net atmospheric
transport of water from land areas to ocean, and the return
flow of fresh water from the land back into the ocean. The
additional components of oceanic water transport are few,
including the mixing of fresh water through the oceanic
boundary layer, transport by ocean currents, and sea ice
processes
• Evaporation – Precipitation + Runoff = surface salinity of the
ocean
Water – Impact on oceans
• The ocean holds 97% of the total water on the planet.
Besides affecting the amount of atmospheric water
vapor and hence rainfall, evaporation from the sea
surface is important in the movement of heat in the
climate system.
• The ocean is one of Earth's most valuable natural
resources. It provides food in the form of fish and
shellfish—about 200 billion pounds are caught each
year. It's used for transportation—both travel and
shipping. It provides a treasured source of recreation
for humans. It is mined for minerals and drilled for
crude oil.
Water – Regulating in an aquarium
• When cleaning your aquarium, you should just
remove part (10-15%) of the water and
replace it with fresh, dechlorinated tap water.
While you are doing this, you should use your
siphon to suck up some of the gunk that
collects in the gravel and decorations.
Oxygen Cycle
Figure 1. Oxygen dynamics in coastal waters. Processes that increase dissolved oxygen concentrations are shown with green boxes. Processes
that decrease dissolved oxygen concentrations are shown with orange boxes.
Oxygen – Important steps
Stage 1 – Entry
-diffusion; oxygen is constantly entering the water from
the air, aeration; oxygen is circulated through and
dissolved in water, and photosynthesis by plants and
algae
Stage 2 – Uptake
Respiration by animals and degassing – breaking down
CO2 and other compounds
Stage 3 – Removal
oxygen leaves the ocean surface and enters the
atmosphere by diffusion
Oxygen – Impact on oceans
• Oxygen in water is known as dissolved oxygen or DO.
• Adequate dissolved oxygen is necessary for good water
quality. Oxygen is a necessary element to all forms of life.
Many natural processes require adequate oxygen levels in
order to provide for aerobic life forms.
• Fish and aquatic animals cannot split oxygen from water
(H2O) or other oxygen-containing compounds. Only green
plants and some bacteria can do that through
photosynthesis and similar processes. Virtually all the
oxygen we breath is manufactured by green plants. A total
of three-fourths of the earth’s oxygen supply is produced by
phytoplankton in the oceans.
Oxygen – Regulating in an aquarium
• The exchange of oxygen is facilitated by water
movement. In the aquarium, this movement is created
by the flow of water exiting from the filter or by the
bubbles that arise from air circulated by a motorized
pump through porous aerating devices known as “air
stones.” The oxygen that is contained in the bubbles
created by air stones or other forms of mechanical
filtration is lost to the air and does not add to the
dissolved oxygen content of the water. By disturbing
the water surface, these bubbles and other forms of
water movement create turbulence, which allows
atmospheric oxygen to dissolve into the water.