Simulating wild conditions

Ideally, an aquarium’s conditions will be completely the same as in the wild. Although a perfectly balanced ecosystem in an aquarium can never be maintained (even in the nature), the goal of the aquarium keeper is to create an aquarium environment in which the ecosystem is balanced as closely as possible.


Preventing systemic shock

One way that the balance of the aquarium can be severely disrupted is through a systemic shock. This can be caused by factors such as temperature fluctuations, addition/removal of chemicals and organisms.


An aquarium is a system

Its important to think of your aquarium as more than just water providing a medium for fish to live, eat and swim. Every single component of your aquarium plays a unique function in the ecosystem, from the algae to the zooplankton. For example, the algae in the aquarium are responsible for the production of oxygen, absorb carbon dioxide and can also provide a food source for particular fish species. In exchange,the algae gain helpful nutrients from respiration activities of the fish, gaining useful chemicals such as nitrogen.


Benefits of a large tank

As stated many times before on this website, raising fish in a large aquarium is one method to balance out any changes which can occur to help maintain equilibrium conditions. For example, if a single fish were to die in a small tank (say 10 litres), a tremendous change in equilibirum conditions would be present, the flow of nutrients and energy would be completely changed, the organisms in the ecosystem would have to undergo massive change to regain energy flow and balance, likely causing large scale death of fish tank organisms. This would completely disrupt the aesthetic purposes of the aquarium as the new result would be completely different from what the owner intended. On the other hand, if a single fish were to die in a large, 100 litre fish tank with several other fish then the change in the ecosystem would be much smaller and more replaceable. The single fish would no longer be the sole living contributor/influencer in the aquarium, its death would cause a fraction of the ecosystem to be changed, other dependent/supporting organisms would only be affected marginally without causing a significant disruption to the tank as a whole. This is why a larger tank can support a great ecological balance – it can house more organisms which are less dependent on each other.  


Dilution of chemicals

Another large-tank benefit – the great volume of water can dilute chemicals. Ammonia released by fish respiration can be spread over a larger area. Any pollutants from any source are usually highly dissolvable in water, a larger fish tank holds more water allowing concentration to be lower. If the foreign substance is not dissolvble, eg (cooking oil from hands after food preparation), the floating pollutant will be much thinner as it spreads over the surface which will reduce the handicap on surface gas exchange.


Gaseous exchange in the aquarium

Another important factor in the aquarium is the presence of a diverse variety of nutrient cycles. Oxygen and Carbon dioxide are important chemicals which are essential to the functioning of a successful ecosystem. Gaseous exchange occurs at the surface of the water when bubbles are formed and chemicals are absorbed and released between the atmosphere and water. In nature, this occurs through any movement of the water that generates air bubbles (eg wave waterfalls, rapid flow onto a hard object). Carbon dioxide also escapes into the atmosphere through water bubbles when flowing water collides. Another important nutrient cycle which is often neglected is the phosphate cycle. This involves the exchange of micronutrient chemicals such as sulfur and iron which are critical elements which enter and exit as waste. An appropriate handling of the nitrogen cycle as well as a supply of an adequately balanced food source and biological loading is enough to keep the essential nutrient cycles well balanced.


Regular maintenance to prevent infection and disease

Preventing bacterial infection and disease is another important factor in keeping an aquarium healthy. A true aquarium lover will look at their fish everyday for pleasure, in doing this, take some time to notice any signs of stress or disease. By observing fish everyday, you can develop a good perception of baseline behaviour and appearance, any deviation from the norm indicates a potential issue.


Changing tapwater in an aquarium

Typical weekly maintenance of an aquarium involves changing 10-20% of the water, cleaning the gravel and any other substrate of the aquarium (do this with clean aquarium water or distilled water, chlorinated tap water will be may kill beneficial aquatic bacteria). You can use treatment products which remove harmful chemicals from tap water.


Aquarium vacuums

A very helpful tool is an aquarium vacuum, this can remove uneaten food and other pollutants while causing minimal disruption to the aquatic ecosystem. This is usually powered by a hand operated pump which will cause a suction to create a waterflow to remove lightweight aquatic waste/pollutants.


Water pH

pH is used to measure the amount of acidic and alkali components in a fishtank. Hydrogen ions cause the water to be acidic whereas hydroxide ions cause the water to be basic. The addition of hydrogen ions will lower the water pH, increasing acidity while addition of hydroxide ions will increase the pH of the water, making it more alkali(basic).


To describe pH in terms of human senses, an acidic liquid will be zany and have a slight sting (lemon juice, vinegar) whereas an alkali liquid will be bitter and foamy (soap, washing liquid). Fish species have a different preferred pH level depending on were they evolved. Generally speaking, saltwater fish prefer a higher alkali pH whereas freshwater fish prefer a lower pH range, between 5.5 and 7.5.

pH levels are not constant, they vary even between day and night, becoming more acidic during the night and more alkali during the day.


Anything can change the water’s pH, such as the addition of a new substrate or organism (fish and aquatic plants).


Rough pH preference of freshwater aquarium fish

  • Angelfish – 7
  • Goldfish – 7
  • Hachetfish – 6.5
  • Neon Tetra – 6
  • Plecostomus – 6
  • Silver Dollar – 6.5
  • Tiger Barb – 6.5
  • Zebra Danio – 6.5


Generally, a pH of around 6-7 is fine for the majority of freshwater fish.


Effects of pH in the aquarium

High alkaline – Gill function impaired, fish will dart back and forth rapidly to increase water exposure.


High acid – Production of excess mucous to protect their bodies against toxic elements. High also causes behaviours such as gasping, hyperplasia (skin and gill thickening) and eye damage.


Increasing aquarium pH

First of all, only add tiny amounts of chemicals to aquariums to adjust the pH. It is advisable to use an electronic pH monitor, even test out your pH adjusting techniques in a water bucket beforehand to ensure that you do not accidentally add too many chemicals. Like always, a larger aquarium is always better than a smaller aquarium for this task.


Adding baking soda is the most common method to increase the aquarium’s pH. 1 tbsp of baking soda per 5 gallons is a safe amount of small increases. Spread the baking soda evenly over the surface of the water and allow at least 10 minutes for admixture to occur.


Even better, scoop out some water from your aquarium beforehand. Mix the baking soda into this water thoroughly before adding it back into your aquarium, water dissolves into more water far better than baking soda powder.


Decreasing aquarium pH

Do not add vinegar, lemon juice or oranges to the aquarium.

Peat moss is the most popular method used to lower the pH of an aquarium. Place the peat moss into a mesh bag, place it into your filter if it is big enough. If not, placing clean peat moss directly into the water also works. This may cause temporary discoloration of the water, don’t worry, the color will return to normal soon, adding activated charcoal may cause the water to return to a normal color faster than normal.


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