#nitrogen cycle

'Cycling' refers to the cycle by which the toxin ammonia, which is excreted as waste by organisms, before it is turned to nitrite and then to nitrate by biological actors. In aquarist parlance 'cycling' refers to the process and duration of time, during which the nitrogen cycle becomes established and stable. Properly the cycle continues throughout the operation of the aquarium.

Ammonia, which contains nitrogen, is the principal excretory product of living animals, and they void it because it is a toxic byproduct of their own metabolic processes. Human urination is an example of a way in which animals lose excess ammonia, but other kinds of animal may excrete ammonia by means of different methods.

Fortunately other organisms can find a positive use for ammonia, which animals don't want. Their own metabolisms create nitrite from the ammonia they intake, by breaking it down and adding oxygen to the nitrogen. Then yet more microscopic organisms convert the nitrite to the similarly named and chemically related nitrate, which must also be maintained at low levels, but is far less harmful. Traces of nitrate are in fact beneficial to some aquarium organisms.

The nitrogen cycle originates from the decomposition of amino acid, and this is why test kits are available to test for dissolved organics, which are not themselves inherently harmful, but their buildup indicates strain upon the system. How much strain is acceptable depends on the kinds of animals that are living in the aquarium. There isn't really a single standard as to when there are too many dissolved organics, or even nitrate. But regular and sensibly proportionate water changes, help to keep both under control.

Because it involves the processes of different organisms, the nitrogen cycle is very obviously an ecological, as well as a chemical phenomenon. Both the natural processes of the cycle, and the technology by which the effects of the benign organisms are maximised, are known as biological filtration, or biofiltration. It is different from physical and chemical filtration, although the functions of filter media may overlap.

The good bacteria that are involved, colonise available surfaces throughout the aquarium. They are present on rocks and on substrates such as sand and gravel. Similarly they colonise sponges and various proprietary items such as 'bio balls'. At this point, I wish to explain the introductory principles of biofiltration, not to cover its different expressions. It is however worth pointing out, the more the better.

Stocking levels are problematic principally because the living animals themselves create strains upon the biofiltration. Furthermore they require inputs of food, excesses of which contribute to dissolved organics, and therefore the nitrogen cycle, when they are uneaten - thus, messy feeders create more bioload than other organisms, lowering the carrying capacity of the aquarium system.

Feeding behaviors thus determine the 'footprint' animals have on the biofiltration in their aquarium, moreso than their size. It is also the mass of an animal that contributes to its output of wastes, moreso than any single dimension, such as its total length. Another determinant is the metabolic rate of the animal in question, which determines the speed at which its wastes are generated and churned out into the water.

The nitrogen cycle is also why overfeeding is bad, because excess food must inevitably decompose. By definition, the aquarist can't be overfeeding, from the perspective of the nitrogen cycle, when the supplied food is being eaten; overfeeding as in overeating is a different problem. However if feeding your livestock and keeping them healthy begins to stress the cycle, then you have too much bioload in your aquarium.

Often in marine aquariums, 'live rock' and 'live sand' are mentioned. These terms mystify many people, although they are relevant to filtration. The rocks and sand in question are substrates already colonised by microscopic organisms, as play a role in the nitrogen cycle. All items already this colonised are thus 'live' biofiltration media.

Unfortunately there is a misconception that 'live' rock needs transporting from the sea. Such rock is shipped damp but emersed, killing benign and desirable organisms, and necessitating a period called 'curing' in which photosynthesizers are denied an energy source, and further mortality and decomposition ensues. The result is that only 'tough as boots' organisms survive, and some of these species are harmful to corals and such.

Clearly despite the appeal of 'live rock' as a ready made, natural reef, it's use is problematic and self defeating. A distinction just be made, between the use of 'living' filtration media, and the importation of artificially depauperate microenvironments for aquariums. It is better to take rock and sand from an established reef tank instead, to avoid unwanted guests. Although even impoverished live rock can introduce interesting and useful 'friends', these can arrive also from established, nuisance-free tanks

A counterpart to the use of live rock and sand in reef aquariums, is the Walstad style of freshwater aquarium. The Walstad type of tank is one in which living plants and soil substrates are employed instead of artificial filtration; more common than a strict Walstad setup, is a hybrid system that employs both naturalistic and 'normal' approaches in its running.

🐠🌿 Dive into the world of freshwater aquariums! Discover the secrets of cycling and the nitrogen cycle, and set up your tank like a pro with our beginner-friendly guide. 🐟🏞️ #aquariumenthusiast #freshwateraquariums #fishkeeping

Welcome to the fascinating world of freshwater aquariums! As a new aquarium enthusiast, it’s essential to understand the importance of properly cycling your tank. In this beginner’s guide, we’ll unlock the secrets of the nitrogen cycle and help you avoid common pitfalls, ensuring a healthy and thriving aquatic ecosystem for your underwater friends. Understanding the Nitrogen Cycle The nitrogen…

The Nitrogen Cycle!

Review: The Swamp Thing #14

Review: The Swamp Thing #14[Editor’s Note: This review may contain spoilers] Writer: Ram VArt: Mike PerkinsColors: Mike SpicerLetters: Aditya Bidikar   Reviewed by: Matthew B. Lloyd   Summary Hal Jordan, Green Lantern assists Levi in infiltrating the surrounding plant forces in an attempt to stop worldwide destruction.  Hoping to refocus the surrounding forces, Levi has to lose himself in the…

Naturally Helpful

A decomposer is an organism (especially a soil bacterium, fungus or invertebrate) that breaks down dead or decaying organisms (e.g. in compost heaps). This process is called decomposition.

Many bacteria & fungi are decomposers. They release chemicals (nutrients) that plants can then absorb, and form an important part of the carbon & nitrogen nutrient cycles.

Decomposers release carbon from the dead matter into the atmosphere, in the form of CO2 gas. Plants then absorb the carbon dioxide gas as they manufacture food.

Decomposers return nitrogen to the atmosphere via their actions. They break down the complex nitrogen compounds in dead organisms & animal wastes, which returns simple nitrogen compounds to the soil. Plants can then use these compounds to make more nitrates. Overall, crop productivity is increased.

Nitrogen fixation is any natural or industrial process that causes free nitrogen (N2 gas in the air) to chemically combine with other compounds, and thus form compounds that are more reactive (e.g. ammonia, nitrates and nitrites).

Plants like clover have nitrogen-fixing bacteria in their roots. These bacteria carry out the above process, converting N2 gas from the air into nitrates. This also increases crop productivity.

Specialized bacteria that live in lumpy nodules on clover roots help the plant fix nitrogen from the air.

Cellulose is the main constituent of plant cell walls, and vegetables fibres such as cotton. It is an insoluble solution, and humans are incapable of digesting it.

Herbivores such as cows & pigs have cellulose-digesting bacteria in their gut. These bacteria help to break down the thick cell walls of plant tissue, thus giving the animal extra nutrition.

Optical microscope images of celluloses.

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Biotechnology

Humans have found many ways of using micro-organisms to produce foodstuffs, better crops, medical drugs and consumer products. This use of microbes for human ends is called biotechnology.

In its broadest sense, biotechnology is the commercial exploitation of living organisms or their components (e.g. proteins). Basically, it is technology that utilizes biological systems.

Yoghurt bacteria convert lactose sugar in milk to lactic acid. The lactic acid solidifies the milk into yoghurt.

The bacteria used to make yoghurt are Lactobacillus delbrueckii subsp. bulgaricus and Streptococcus salivarius supsp. thermophilus. They are classicied as lactic acid bacteria.

Other bacteria are involved in curdling milk for cheese-making.

Pharmaceutical companies use genetically-engineered bacteria to produce chemicals for medical drugs. Special bacteria are used to produce insulin, which diabetics use to control their blood sugar levels.

Yeasts are an important group of fungi. They convert sugar into CO2 and alcohol via fermentation (a form of anaerobic respiration). Yeasts are used to make bread rise, and ferment beer & wine.

Yeast making bread rise via fermentation.

Some fungi are used to produce chemicals called antibiotics.

An antibiotic is a type of antimicrobial substance that inhibits the growth of bacteria, or destroys bacteria. Antibiotics are the most important type of antibacterial agents for fighting bacterial infections.

Some viruses are used to control pest organisms. Calicivirus (RCD) was illegally released in NZ by farmers to control rabbit populations. This use of microbes is called biological control.

Biological control (also called biocontrol) is a method of using other organisms to control pests. It relies upon natural mechanisms (e.g. predation or parasitism), and typically involves an active human management role.

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Harmful Micro-Organisms

A pathogen is a microbe that causes disease. Pathogens are also called infectious agents, because they cause infections.

Other microbes cause harm by damaging foodstuffs, crops and fabrics. They aren't classified as pathogens because while they do cause harm, they don't cause disease.

All viruses are pathogens. They cause many human diseases, from colds and flus to serious diseases such as polio, hepatitis B and AIDS.

Some bacterial species cause food to rot. You can see colonies of bacteria as shiny spots on meat that has gone off.

Listeria bacteria (sometimes found in shellfish) can cause food poisoning or damage foetuses.

A 3D illustration of Listeria monocytogenes, the species of pathogenic bacteria that causes the infection called listeriosis.

Different fungal species can cause make food rot (e.g. bread mould & potato blight), make fabrics go mouldy, or cause wet rot in timber.

Some species of fungus infect humans (e.g. thrush & athlete's foot).

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Antiseptics and Disinfectants

An antiseptic is an antimicrobial substance that kills or inhibits the growth of micro-organisms on intact skin. An antiseptic is applied to living tissue or skin, and will reduce the possibility of infection, sepsis or putrefaction.

A disinfectant is a chemical substance that is used to destroy (or inactivate) micro-organisms on inert surfaces. Disinfectants are generally strong chemicals used around the home.

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