Nitrogen Cycle And Aquarium Cycling Including Nitrification, Denitrification, And Cycling Methods

INTRODUCTION:rock (in Marine Aquariums) are excellent sources of
Nitrogen is an element vital to all life processes onbio filtration in larger aquaria. Bio-Wheels are very
Earth. Nitrogen is very important in our biosphere,popular, but in my tests in my maintenance business
where nitrogen comprises 78% of the atmosphere,they are VASTLY overrated. They tend to
and is part of every living tissue. It is a component ofaccumulate hard water deposits and stop and even
amino acids, proteins and nucleic acids. With thewhen they are working my tests have shown little
exception of carbon, nitrogen is the most universaldifference in aquariums when they are removed as
element of life. Life could not exist without nitrogen.compared to sponge filters or wet/dry filters.
Nitrogen is essential for organic development;Canister filters are also good sources for nitrification
nitrogenous compounds are also required by someas long as the proper media is used (such as ceramic
organisms for metabolic functions and respiration.rings) and the media is not packed too tight and is
All living organisms, from fish to plants, have greatrinsed regularly.
quantities of assimilated nitrogen in their tissues.DENITRIFICATION:
Nitrogen is a fundamental ingredient for the formationIs the process of converting Nitrates (NO3) in to
of proteins and nucleic acids. Every organism youNitrogen (N2), which is dispersed into the atmosphere.
place in your aquarium adds nitrogen; from fish toThis process can take place in an environment
coral, to live rock, to plants.without oxygen by anaerobic bacteria. This process is
The introduction of food also adds nitrogen. Dead ormore common in Marine aquaria and takes place in
alive, they are organic masses, and possess thefine #00 sand, , live rock, or "aquarium mud". In
same nitrogenous attributes as the fish, plants,freshwater aquariums this process often produces
invertebrates you added to your aquarium.deadly Hydrogen Sulfide, but by maintaining an
Inorganic nitrogen is added two ways: theoxygen level above 1 ppm, this can be avoided.
atmosphere and new water. Atmospheric nitrogenPlants roots are great for maintaining this balance of
(N2) is incorporated into our aquarium water by wayoxygen in the gravel for proper Nitrate removal
of nitrogen fixing bacteria and by cyanobacteria asA thicker layer of coarse gravel utilizing a "void
ammonia (NH3). Inorganic nitrogenous compoundsspace" called a plenum is often used for Nitrate
from our tap or well water also enter our aquarium,removal in Saltwater and even freshwater aquariums.
often as Nitrates or Nitrates. Reverse Osmosis canThese are not to be confused with under gravel
remove much of this.filters.
NITRIFICATION:SUMMARY OF LEVELS;
When an organism dies, nitrogen is moved from plantIn healthy aquarium ammonia and nitrites should be at
or animal into the inorganic chemical ammonia by the0 ppm
process of bacterial decay. Ammonia is also producedIn a healthy freshwater aquarium Nitrates should be
by bacteria in the breakdown of protein. This process15-50 ppm (below 15 ppm is not healthy for planted
is called Mineralization and is the end result of thefreshwater aquariums).
metabolism of food. However, ammonia is producedIn a healthy Saltwater fish aquarium nitrates should
from both metabolism and mineralization. Thebe below 40 ppm.
decomposition (mineralization) process produces largeIn a healthy Marine Reef aquarium nitrates should be
quantities of ammonia (NH3) through the process ofbelow 20 ppm (or even less).
ammoniafication. Heterotrophic microbes utilize theAQUARIUM CYCLING:
organic compounds of decomposing matter as theirThese major additional benefits result from the
carbon source. Ammonia (NH3) is the byproduct ofconstant removal of Nitrate by bacterial action in the
this consumption. Ammonia, in its neutral state, existsplenum. My preferred cycling method (it was not in
as ammonium (NH4+).one of the links) is to transfer filter media (sponges
Ammonia (NH4) is assimilated in more than one way.work best) from an established aquarium along with
Plants (such as Hornwort) and algae can assimilatesome gravel, then introduce the fish SLOWLY
ammonia and ammonium directly for the biosynthesis.starting in a day or two. The method of adding
The remaining bulk of decomposed byproducts are"aged" media is much faster (you still have to take it
utilized by bacteria in a process called nitrification.slow), and provides all the necessary bacteria, the
Ammonia does not last long in a healthy aquariumonly negative is adding disease pathogens to your
environment, fortunately. Nitrifying bacteria such asaquarium, but I have rarely encountered this problem.
Nitrosomonas quickly break down ammonia into lessTo prevent this transfer of disease pathogens and
toxic Nitrite (NO2). During this process, specificparasites, only use a media source where no new
species of nitrifying bacteria strip the ammonium offish have been added in 30 days, ALL water
its hydrogen molecules as an energy source. Oxygenparameters are good, and if possible has UV
molecules are then affixed to the stripped nitrogen,Sterilization (although not necessary).
forming the oxide nitrite (NO2).Also keep in mind that many pathogens such as
Another group of bacteria (Nitrobacter ) utilize thepseudomonas are usually present in a healthy
enzyme nitrite oxidase that is then responsible foraquarium, but when fish are stressed, the fish are in
converting nitrite into nitrate (NO3). This nitrate canpoor health due to poor feeding and lack of proper
either be used by plants as a nutrient source, or canminerals, and/or water conditions are less than
be further broken down into nitrogen gas (N2)desirable- these pathogens will be opportunistic and
through the activity of anaerobic bacteria such ascause a disease in the fish.
Pseudomonas .We used this method for our Aquarium Maintenance
It should be noted, that without oxygen (nitrificationroute for years and never lost a fish to Ammonia or
is an oxidative process), none of this process cannitrite poisoning, and disease transfer was minimal.
take place.There are many products for cycling available too,
It should also be noted that in recent studies thebut most in my opinion do not work well (although
Nitrosomonas and Nitrobacter responsible Freshwaterproperly cared for BioSpira is effective).
nitrification are NOT the same in saltwater.Another method is fishless cycling where un-scented
BIOFILTRATION:pure ammonia is poured into the aquarium (3-5 drops
Nature can pack a lot of bacteria into small places,per gallon pure ammonia) so as to bring your
which is to the advantage of the aquarist. Forammonia level to 4-5 ppm. Then it takes about 3-8
bacterial growth, all that is required is ammonia andweeks for the aquarium to cycle. Although this
oxygenated water. This is the beginning of themethod is growing in popularity, I do not recommend
nitrogen process and the growth of bacterial colonies.it, not because it does not work (it does), but
Remember you need oxygen and a lot of surfacebecause human nature is to want to add fish sooner
area for bacterial colonies. Wet/dry filters, spongethan the 3-8 weeks it takes for this method.
filters, ceramic media, and loosely packed upperAnother method is the gradual addition of fish food
layers of gravel are all sources for bacterialto an otherwise empty aquarium (no fish). This can
accumulation. If there is not adequate surface area inbe a very effective means of cycling that is
oxygen areas of the filter media or gravel, nitrificationpreferred by many experienced aquarists.
will be poor. Water will follow the path of leastThe method of adding "aged" media is much faster
resistance, so if your filter or gravel has a build-up of(you still have to take it slow), and provides all the
non-nitrifying bacterial slime or is packed to tightly,necessary bacteria, the only negative is adding
nitrification will not be achieved. Sponge Filters ordisease pathogens to your aquarium, but I have
Pre-Filters are an inexpensive filter medium forrarely encountered this problem.
colonies of nitrifying bacteria. Wet/dry filters and live