Section 3 - Things to know about
starting an aquarium
The nitrogen cycle
Before adding fish to your aquarium there is some important information to
understand about how the aquarium water remains clean and healthy enough
for fish to thrive.
The aquarium is a small ‘closed’ environment; this means harmful waste can
build up quickly because there is not enough water volume to dilute the waste,
as would happen in a natural lake, nor is there a constant supply of fresh water to
wash it away, as would happen in a river or stream. The breakdown of fish waste,
excess food, dead plant material and other organic matter will cause invisible toxic
compounds to build up in the aquarium water, unchecked this would eventually
harm your fish. Fortunately there is a natural process called the “Nitrogen Cycle”
which we can recreate in the aquarium to convert the toxic waste into safer
compounds (The diagram below shows how this process works).
This Nitrogen cycle is carried out by essential “Nitrifying” bacteria which set up
home in the biological media in the aquarium filter. These bacteria would naturally
take a couple of months to become established in the filter. During this maturing
period fish keepers often experience fish losses caused by the build-up of invisible
toxic compounds which is referred to as “New tank syndrome”.
Filter
Media
Filter
Media
- Dead plant matter
- Dead livestock
- Uneaten food
All breakdown into
ammonia
Nitrogen Cycle
- Lethal to livestock
- Should always be kept
to zero
- Produced from fish
waste
AMMONIA
- Lethal to livestock
- Poisoning causes fish
to gasp at surface
NITRITE
- Very much safer for fish
- Large macro nutrient
used by plants for
food
- Removed via water
changes
NITRATE
Nitrosomonas bacteria
breakdown ammonia
into nitrite
Nitrobacter bacteria
breakdown nitrite
into nitrate
AMMONIA
u
OXYGEN
u
NITRITE
u
NITRITE
u
OXYGEN
u
NITRATE
u
