Understanding how the organisms in your aquarium function will give you a
better handle on maintaining a healthy environment. Of all the processes to
be familiar with, the nitrogen cycle is among the most important. The
nitrogen cycle, sometimes called "nature's waste management system,"
provides biological filtration in aquatic ecosystems, as well as in
household aquariums. Because the aquarium is artificial and a
representation of an environment where certain occurrences happen
naturally, it is the responsibility of the hobbyist to ensure that the
correct conditions are always present for the nitrogen cycle to stay in
Let's start with the basics of the nitrogen cycle. Essentially, it is a 4-
step process that involves bacteria converting harmful waste.
. Step 1 - Objects in the tank decay. This includes waste products of
fish, plants and invertebrates, as well as dead organisms or uneaten
food. When object decay, ammonia is produced; even at low levels it
can be caustic to the gills and restrict fish of their oxygen supply.
. Step 2 - The ammonia is then consumed by a bacterium called
Nitrosomonas; this process creates another chemical byproduct called
nitrite. Even though the nitrate is toxic, preventing the blood from
carrying oxygen, fish can withstand almost twice the amount of nitrate
than ammonia in their water supply.
. Step 3 - The nitrite is that consumed by other bacteria called
Nitrobacter. It, in turn, releases a less toxic chemical called
. Step 4 - To become a harmless nitrogen gas, nitrate depends on
anaerobic conditions. The requirements needed are not present in most
aquariums, so water changes are necessary to dilute nitrate.
Cycling the tank will be necessary to keep everything running smoothly.
Cycling refers to the process of establishing and maturing the biological
filtration. Typically, new aquariums can be cycled in 2 to 6 weeks, but the
actual length depends on different factors. These factors include the
amount of ammonia produced during the cycling period, the efficiency of
biological filtration, whether live rock or live plants are used, and
whether you boost bacteria colonies with additives.