INTRODUCTION:
Nitrogen is an element vital to all life processes on Earth. Nitrogen is very important in our biosphere, where nitrogen comprises 78% of the atmosphere, and is part of every living tissue. It is a component of amino acids, proteins and nucleic acids. With the exception of carbon, nitrogen is the most universal element of life. Life could not exist without nitrogen. Nitrogen is essential for organic development nitrogenous compounds are also required by some organisms for metabolic functions and respiration.
All living organisms, from fish to plants, have great quantities of assimilated nitrogen in their tissues. Nitrogen is a fundamental ingredient for the formation of proteins and nucleic acids. Every organism you place in your aquarium adds nitrogen from fish to coral, to live rock, to plants. The introduction of food also adds nitrogen. Dead or alive, they are organic masses, and possess the same nitrogenous attributes as the fish, plants, invertebrates you added to your aquarium.Inorganic nitrogen is added two ways: the atmosphere and new water. Atmospheric nitrogen (N2) is incorporated into our aquarium water by way of nitrogen fixing bacteria and by cyanobacteria as ammonia (NH3). Inorganic nitrogenous compounds from our tap or well water also enter our aquarium, often as Nitrates or Nitrates. Reverse Osmosis can remove much of this.
NITRIFICATION:
When an organism dies, nitrogen is moved from plant or animal into the inorganic chemical ammonia by the process of bacterial decay. Ammonia is also produced by bacteria in the breakdown of protein. This process is called Mineralization and is the end result of the metabolism of food. However, ammonia is produced from both metabolism and mineralization. The decomposition (mineralization) process produces large quantities of ammonia (NH3) through the process of ammoniafication. Heterotrophic microbes utilize the organic compounds of decomposing matter as their carbon source. Ammonia (NH3) is the byproduct of this consumption. Ammonia, in its neutral state, exists as ammonium (NH4+).
Ammonia (NH4) is assimilated in more than one way. Plants (such as Hornwort) and algae can assimilate ammonia and ammonium directly for the biosynthesis. The remaining bulk of decomposed byproducts are utilized by bacteria in a process called nitrification. Ammonia does not last long in a healthy aquarium environment, fortunately. Nitrifying bacteria such as Nitrosomonas quickly break down ammonia into less toxic Nitrite (NO2). During this process, specific species of nitrifying bacteria strip the ammonium of its hydrogen molecules as an energy source. Oxygen molecules are then affixed to the stripped nitrogen, forming the oxide nitrite (NO2). Another group of bacteria (Nitrobacter ) utilize the enzyme nitrite oxidase that is then responsible for converting nitrite into nitrate (NO3). This nitrate can either be used by plants as a nutrient source, or can be further broken down into nitrogen gas (N2) through the activity of anaerobic bacteria such as Pseudomonas .
It should be noted, that without oxygen (nitrification is an oxidative process), none of this process can take place. It should also be noted that in recent studies the Nitrosomonas and Nitrobacter responsible Freshwater nitrification are NOT the same in saltwater.
BIOFILTRATION:
Nature can pack a lot of bacteria into small places, which is to the advantage of the aquarist. For bacterial growth, all that is required is ammonia and oxygenated water. This is the beginning of the nitrogen process and the growth of bacterial colonies.Remember you need oxygen and a lot of surface area for bacterial colonies. Wet/dry filters, sponge filters, ceramic media, and loosely packed upper layers of gravel are all sources for bacterial accumulation. If there is not adequate surface area in oxygen areas of the filter media or gravel, nitrification will be poor. Water will follow the path of least resistance, so if your filter or gravel has a build-up of non-nitrifying bacterial slime or is packed to tightly, nitrification will not be achieved. Sponge Filters or Pre-Filters are an inexpensive filter medium for colonies of nitrifying bacteria. Wet/dry filters and live rock (in Marine Aquariums) are excellent sources of bio filtration in larger aquaria. Bio-Wheels are very popular, but in my tests in my maintenance business they are VASTLY overrated. They tend to accumulate hard water deposits and stop and even when they are working my tests have shown little difference in aquariums when they are removed as compared to sponge filters or wet/dry filters. Canister filters are also good sources for nitrification as long as the proper media is used (such as ceramic rings) and the media is not packed too tight and is rinsed regularly.
DENITRIFICATION:
Is the process of converting Nitrates (NO3) in to Nitrogen (N2), which is dispersed into the atmosphere. This process can take place in an environment without oxygen by anaerobic bacteria. This process is more common in Marine aquaria and takes place in fine #00 sand, , live rock, or ?aquarium mud?. In freshwater aquariums this process often produces deadly Hydrogen Sulfide, but by maintaining an oxygen level above 1 ppm, this can be avoided. Plants roots are great for maintaining this balance of oxygen in the gravel for proper Nitrate removalA thicker layer of coarse gravel utilizing a “void space” called a plenum is often used for Nitrate removal in Saltwater and even freshwater aquariums. These are not to be confused with under gravel filters.
SUMMARY OF LEVELS
In healthy aquarium ammonia and nitrites should be at 0 ppmIn a healthy freshwater aquarium Nitrates should be 15-50 ppm (below 15 ppm is not healthy for planted freshwater aquariums). In a healthy Saltwater fish aquarium nitrates should be below 40 ppm.In a healthy Marine Reef aquarium nitrates should be below 20 ppm (or even less).
AQUARIUM CYCLING:
These major additional benefits result from the constant removal of Nitrate by bacterial action in the plenum. My preferred cycling method (it was not in one of the links) is to transfer filter media (sponges work best) from an established aquarium along with some gravel, then introduce the fish SLOWLY starting in a day or two. The method of adding ?aged? media is much faster (you still have to take it slow), and provides all the necessary bacteria, the only negative is adding disease pathogens to your aquarium, but I have rarely encountered this problem. To prevent this transfer of disease pathogens and parasites, only use a media source where no new fish have been added in 30 days, ALL water parameters are good, and if possible has UV Sterilization (although not necessary). Also keep in mind that many pathogens such as pseudomonas are usually present in a healthy aquarium, but when fish are stressed, the fish are in poor health due to poor feeding and lack of proper minerals, and/or water conditions are less than desirable- these pathogens will be opportunistic and cause a disease in the fish.We used this method for our Aquarium Maintenance route for years and never lost a fish to Ammonia or nitrite poisoning, and disease transfer was minimal.
There are many products for cycling available too, but most in my opinion do not work well (although properly cared for BioSpira is effective).
Another method is fishless cycling where un-scented pure ammonia is poured into the aquarium (3-5 drops per gallon pure ammonia) so as to bring your ammonia level to 4-5 ppm. Then it takes about 3-8 weeks for the aquarium to cycle. Although this method is growing in popularity, I do not recommend it, not because it does not work (it does), but because human nature is to want to add fish sooner than the 3-8 weeks it takes for this method.
Another method is the gradual addition of fish food to an otherwise empty aquarium (no fish). This can be a very effective means of cycling that is preferred by many experienced aquarists.The method of adding ?aged? media is much faster (you still have to take it slow), and provides all the necessary bacteria, the only negative is adding disease pathogens to your aquarium, but I have rarely encountered this problem.
For a picture expalining the nitrogen cycle, please visit this URL:Aquarium Nitrogen Cycle
By Carl Strohmeyer
Tags: nitrite, ammonia, water fish, fishless cycling, aquarium, organic compounds, freshwater aquariums, algae, health, Fish, nitrates, feed, freshwater aquarium, protein, aquarist
