NOTES - WATER QUALITY & THE NITROGEN CYCLE IN AN AQUARIUM

• Below is a brief explanation of the nitrogen cycle and its presence in the aquarium
  
• Included are tips to manage and start the process
• With methods to avoid problems and counter act imbalances to the nitrogen cycle
  

The nitrogen cycle is a natural process which occurs in any ecosystem of water. It is nature's way of processing and breaking down organic matter into a bi-product that can be recycled by flora (plants/trees) in and out of the particular ecosystem.

The nitrogen cycle consists of three stages. The first two stages are identical in both fresh and saltwater. The final stage differs slightly as saltwater ecosystems contain a specific anaerobic bacteria which is not present in freshwater. This group of bacteria is capable of further breaking down the final product (Nitrate NO3) of the cycle.

Although the nitrogen cycle is not observable by the naked eye, it is inevitably present in any fish tank, lake, river, ocean or pond. In any new body of water the cycle will not begin until organic matter is introduced. Matter in the form of fish waste (urine/faeces) or decomposing organic material. When such waste is present, the nitrogen cycle will take approximately 4-6 weeks to complete its cycle. From the starting point the waste begins its decomposition and is present in the form of NH3 (ammonia) in the aquarium. A first group of bacteria (Nitrosomonas Sp.) gradually cultivates itself to a number sufficient to handle the given amount of waste and in turn consumes (oxidises) and converts the matter into Nitrite (NO2). Stage 1 of this oxidisation process of NH3 - NO2 generally takes up to 2 weeks. At this time when Nitrite has accumulated, another group of bacteria (Nitrobacter sp) automatically cultivates to again process the nitrite and convert it into the less toxic form of Nitrate (NO3). Stage 2 of this cycle will approximately take another 2 weeks. The final bi-product of the nitrogen cycle being NO3 is now present in the body of water. Although low levels of nitrate is not toxic to the fish it is still a necessity to dilute it via water changes to maximise fish health.

As mentioned before in freshwater ecosystems nitrate is naturally removed via plants, trees and algae who are able to process NO3 as a form of their food source. Without the presence of flora in the natural occurring ecosystems the build up of nitrate would reach levels impossible to sustain aquatic life. In saltwater the slight advantage is that NO3 can actually be further oxidised by a specific species of bacteria. These types of bacterias thrive in oxygen depleted environments found amongst the live rock and coral substrates.

• How healthy and clean your aquarium water is, directly relates to how efficient and balanced the bacteria levels are in your tank.
• The hobbyist must utilise information from the nitrogen cycle and apply their knowledge to practise healthy methods of fish keeping.
• Whenever a new aquarium is setup, it is important you do not overstock the tank. There is no bacteria present, hence provision for the nitrogen cycle to begin and operate must be allowed.
  

GUIDE TO SETTING UP AN AQUARIUM;

• From a bare tank you add water (de-chlorinate), connect and run your filter of choice.
• If housing tropical fish wait for the appropriate water temperature to be reached (a safe time frame would be 24 hours keeping in mind factors such as heater's power and tank capacity).
• At appropriate water temperatures add a few tolerant species to kick start the cycle.
  
• Start feeding in small quantities once daily.

In a matter of 1-2 weeks the ammonia level will have risen to harmful levels but before the next stage of the nitrogen cycle automatically turns over, it is recommended that a partial water change be given now to dilute ammonia levels in the tank and to prevent stress to the fish.

• Give the aquarium a 30% water change preferably extracting water via an aquarium gravel cleaner. (most of the solid wastes and toxins settle in the gravel and the lower levels of the tank therefore requiring you to siphon thoroughly through these areas)
  

In lowering the pollutant via the water change it is now safe to add a few more tank mates and patiently wait for the next stage. At 3-4 weeks of age, ammonia levels in the aquarium will be at a bare minimum, yet nitrite levels will have escalated from 0ppm (parts per million) to very high concentrates (depending on waste load).

• A second water change is now vital to counter act the effects of the potentially dangerous NO2 levels.
  

During the week after the nitrites have reached peak levels and the important 2nd water change has been accomplished the nitrogen cycle will gradually reach its safe zone where NO3 is the final product.

Keeping these instructions in mind, the hobbyist may now understand why water changes and feeding methods are so important to the aquarium's success. Ammonia and Nitrite are very toxic pollutants. They will always be bi products from the ever circling nitrogen cycle and an unbalance in your aquarium will mean the accumulated presence of the mentioned NH3, NO2 and NO3. Any excess food, dead fish or plant debris can cause an imbalance and therefore should be removed when noticed.

• Nitrate NO3 is not toxic in small amounts.
• Ammonia NH3 is toxic and causes irritation to fish by effecting the gills (heavy breathing / redness) and in extreme cases effects the fins, body, eyes and scales. Sudden ammonia spikes are usually the primary cause to many fish diseases. Cloudy water is also a tell tale sign to insufficient bacteria levels. Either there is a fish carcass in the aquarium, excess food or even if too much old water has been extracted, merky/cloudy water will develop from an ammonia build up.
  
• Nitrite NO2 is toxic and causes similar symptoms to that of ammonia poisoning. Along with those effects, under extreme prolonged exposure to high nitrites fish may go into sudden shock (paralysis) and spiralling motions leading to sudden death.
  

Test kits are available for you to purchase at your local retail stores to help you visualise which stage of the nitrogen cycle your tank is at. PH (power of hydrogen), Ammonia and Nitrite kits are extremely important, a worthy investment and great indicators for how well your aquarium is established.

Of course these are only guidelines for how to maintain optimum conditions for healthy and vibrant fish. There must be a million methods to fish keeping but none can be condoned incorrect as fish are quite easy to keep. Patience is still the most important key to setting up a new aquarium and artificial aid in the form of biological products is available to help speed up the cycle.
Practising good methods will eventually enable you to perfect maintenance routines for your fish tank.

Fish can build up tolerance levels to suit their environment meaning that enthusiasts that have neglected their tanks for months without any water changes or adjustments are still able to keep their scaled friends alive. The fish will adapt but this is definitely not recommended and is 100% not healthy for the fish. Imagine the aquarium as their home, their kitchen, living room and importantly their toilet. How can anyone bare to let their beloved aquatic pets swim around in their concentrated faeces and urine for lengthy periods of time. Another result from lack of maintenance to your fish tank is that whilst your fish are constantly eating, breathing and going to the toilet in the aquarium, the carbonate hardness levels gradually deplete which then directly effects the PH level. The rate at which the PH drops and the level that the PH may drop to is determined by how long the tank is neglected for and how heavily stocked the tank is. If fish (fry or adults) have become accustomed to bad water (eg. PH: 5.8, NO2: 20ppm, NO3: 150ppm) then it is extremely difficult and time consuming to relocate and adjust them to new environments.

AUTHOR'S EXPERIENCE WITH A FISH LESS CYCLE

A project was acquired a few years ago where I had to set-up a large display tank for a major event and was only allowed 10 days from delivering the tank on site to have it ready for a grand opening. Being limited with time I had two options to consider. Either 1, fill the tank with 60 - 80% of old established aquarium water (1500L) or option 2, improvise. I decided to transfer 100kg of gravel from an old existing fish tank and also an entire amount of filter medium from 2 old filtration systems (mini-reefs).
The process was putrid to visualise and the odour was disgusting too. I had to minimise transit time as the longer the medium was left unattended the good bacteria I was aiming to re-cultivate would all die.
Within 36 hours the ammonia was at an extremely high level and the water was very cloudy.
I then immediately did a 40% water change to help dilute pollutants present in the aquarium. I then added a dosage of cycle which is a bacteria supplement and waited for the next stage.
In another 72 hours the ammonia levels had reduced by a considerable amount and nitrites had begun to appear. At 5 days from the initial setting up of the aquarium I again did a water change to this time dilute the nitrite levels and continued a second dosage of cycle.
I then added 200kg of rock work that I again gathered from existing aquariums and proceeded to decorate the display aquarium.
By day 8, the nitrogen cycle had circulated to the nitrate stage and the aquarium water was crystal clear. Contractors had begun building a facade around the outer skirts of the aquarium in preparation for the event's opening.
On this same day I extracted 20% of the water and was extremely thorough in performing a gravel clean on the aquarium. I then introduced 30 adult cichlids and catfish to the aquarium and released all the bags of water that the stock arrived with.
At my deadline of day 10, another 30 adult fish were adapted in to the aquarium and the last water change was performed before the reveal day.
During the next two weeks while the aquarium was being displayed feeding was kept at bare minimals, once every 4th day and water changes were incorporated 2 hours after feeding.
Water parameters were monitored and with all minor interruptions considered the project was a great success.

Most importantly the fish handled the relocation very well. The water remained clear for the entire two weeks bar some algae build up on the glass due to phosphate levels that managed to escalate and over exposure from metal halide lighting.
The methods I imposed were only successful as I was able to introduce existing filter medium and substrate and constant water changes were performed at the sight of relevant toxins.

To conclude this article, no matter which method you decide to exercise you must remember to be patient. Understand the nitrogen cycle's occurrence in your aquarium and know that any irregular feeding or introduction of load on your tank will cause slight imbalances and know what you should do to counteract problems. Water changes are very healthy for your tank provided you never extract too much old water as this might cause vast fluctuation in temperatures and even stress fish. Depending on how enthusiastic you are weekly water changes of 10% will bring rapid fish growth and exuberant results in breeding and housing of your aquatic pets.

I hope my above notes were not too complex.
I hope I was successful in combining years of my knowledge and relaying it for the reader to take away, practise and even improve on my own mentioned methods.

HAPPY FISH KEEPING!

NOTE: Caption photo shows first stage of the process as ammonium. This form of ammonia, NH4 is not toxic to the fish however ammonium will only be present if your aquarium's PH level is below 7. In any instances where the PH level is higher all decaying organic matter will test positive as NH3 Ammonia.

Photo courteous of fishlore.com