Suitable water values in the aquarium: OASE online laboratory 

This article provides examples of different aquarium types and their ideal values, from community and biotope aquariums to Aquascapers, to help you keep a better eye on the measurements in your aquarium.  

Community aquariums 

A community aquarium contains various animal species that would not meet in the wild. For example, neons from South America and gouramis from Asia can be kept together in an aquarium. It is important to know that this requires a certain amount of compromise in terms of the water values at which the different species feel comfortable.

Discus tank 

Discus fish are members of the cichlids family and originate from South America. These fish prefer roots and woods in the aquarium, which they can use as hiding places, and they should be kept in groups of at least five. Due to their origin, these fish like warm water temperatures.

Goldfish tank

Goldfish are members of the carp family and are comparatively undemanding in terms of water temperature as they do not require a heater. The aquarium should be minimalist, have no sharp-edged substrate and provide plenty of space for swimming. You can add style to the tank in a variety of ways. Aquatic plants should be used with caution, as goldfish also like to nibble on them.

South American tank

This type of aquarium focuses on South America as a natural habitat. It often has softer water and a higher water temperature. The tank is often furnished with root woods and hiding places.

Asian tank

This type of aquarium focuses on the continent of Asia. There is a massive choice of species and colours available. Dwarf shrimps, for example, also originate in Asia, but are used in a wide variety of tanks. The habitat may contain roots and/or stones.

Malawi tank

The Malawi tank will contain aquarium inhabitants from East African species, mainly cichlids. The habitat in these tanks is characteristic, as it includes stone formations with less use of aquatic plants and wood.

Biotope tank

Biotope aquariums create habitats that are precisely based on a natural environment. Not only is the habitat reproduced as faithfully as possible, but living creatures, aquatic plants and decorations such as stones and wood from the same region are also used.

Aquascape tank

Aquascaping focuses on nature. Aquarium inhabitants are in the background, whilst nature forms the focal point. Miniature landscapes are created in which each stone is precisely positioned, each plant is precisely set and every additional element is precisely placed. The process culminates in a true work of art.

Notes

 

Temperature

The required temperature always depends very much on which inhabitants and plants you have in your aquarium. The ideal temperature for most tropical aquarium fish is between 23 and 26°C. However, there are also some fish that need lower or higher temperatures, such as rainbow shiners, which prefer cooler temperatures of 18 to 20°C, or the heat-loving discus, which starts to feel comfortable in temperatures of 28 to 30°C. Most plants also prefer things not to be too cool and prefer temperatures between 20 and 27°C.

 

pH value

The pH value or "acidity level" indicates how acidic or alkaline the water is. It is a measure of the concentration of the acidic or alkaline components in an aqueous solution. Pure water reacts neutrally and has a pH of 7. If acidic components dominate, the pH value falls below 7. If there are more alkaline components, the pH value rises above 7.

 

General hardness

General hardness (GH) is the amount of magnesium and calcium salts dissolved in the water. If there is only a small amount of these salts, the water is referred to as soft, but if the amount is larger, the water is described as hard. The value is given in degrees of German hardness, with 1°dH equating to 10 mg/l of dissolved calcium oxide.

 

Carbonate hardness

The carbonate hardness (KH) indicates the content of hydrogen carbonate ions in the aquarium water and is closely linked to the pH value. The hydrogen carbonates assume a buffer function in the aquarium water to prevent sudden changes in the pH value. If the hydrogen carbonate ion content is too low, a potentially life-threatening fall in the pH value for many fish and plants may occur (drop in acidity). The hydrogen carbonate ions are in equilibrium with the carbon dioxide dissolved in the aquarium water. Carbon dioxide is essential as a food source for plants in photosynthesis. This means that the correct carbonate hardness is also extremely important for plant growth.

 

Ammonium/ammonia

The ammonium ion results from nitrogen mineralisation. Nitrogen, which is organically bound in food residues and excrement (for example, in proteins), is converted by protein-splitting bacteria and released in the form of inorganic ammonium ions. Depending on the pH value, there is a balance between ammonium ions NH4+) and ammonia (NH3) in the water. Ammonium ions dominate at pH values below 7, while ammonia is increasingly present when the pH value exceeds 7. Ammonia is very dangerous as it interferes with the respiration of aquarium fish and blocks vital functions. Aquatic plants use ammonium as a source of nitrogen. In a healthy, established aquarium filter, ammonium is quickly oxidised by nitrifying bacteria from nitrite to nitrate. If this process chain is disrupted, a sudden increase in ammonium/ammonia may occur.

 

Nitrite

Nitrite ions (NO2–) and nitrate ions (N03–) are produced in a process of decomposition of nitrogen compounds in the presence of oxygen called "nitrification”. Nitrite is a highly toxic phase for fish and molluscs. Its physiological effect prevents oxygen transport in the blood and blocks cell respiration. As a rule, nitrite produced from ammonium is rapidly oxidised to comparatively non-toxic nitrate by nitrifying bacteria. An unwanted increase in nitrite concentration may occur if this bacterial oxidation process is prevented, for example by new filter material. Nitrate is the final stage of nitrification and has a lesser effect on the life and well-being of fish and molluscs. The main source of nitrogen compounds in the aquarium is proteins from food residues as well as excrement and organic decomposition products. Nitrate concentrations which occur in the aquarium are usually non-toxic, but increased algae growth may occur at elevated concentrations.

 

Nitrate

Nitrite ions (NO2–) and nitrate ions (N03–) are produced in a process of decomposition of nitrogen compounds in the presence of oxygen called "nitrification”. Nitrite is a highly toxic phase for fish and molluscs. Its physiological effect prevents oxygen transport in the blood and blocks cell respiration. As a rule, nitrite produced from ammonium is rapidly oxidised to comparatively non-toxic nitrate by nitrifying bacteria. An unwanted increase in nitrite concentration may occur if this bacterial oxidation process is prevented, for example by new filter material. Nitrate is the final stage of nitrification and has a lesser effect on the life and well-being of fish and molluscs. The main source of nitrogen compounds in the aquarium is proteins from food residues as well as excrement and organic decomposition products. Nitrate concentrations which occur in the aquarium are usually non-toxic, but increased algae growth occurs at elevated concentrations. The right nitrate value is particularly important for healthy, abundant plant growth. This means that significantly higher values are required in a heavily planted aquarium than in a less heavily planted aquarium. Values of 5 to 15 mg/l would be ideal for a typical community aquarium with fewer plants. In heavily planted tanks such as Aquascaping or Dutch style plant aquariums, values of 20 to 30 mg/l are often desirable. In biotope aquariums, which often contain no plants at all, however, attempts should be made to keep the values as low as possible. In simple terms, nitrate is an important nutrient for the plants, but it should be kept as low as possible for the fish. To prevent unwanted algae growth, it is important that the values are neither too high nor too low.

 

Phosphate

Phosphates are important nutrients for all plants and are essential for the energy metabolism of every living cell. Phosphates enter the aquarium water through food, but also through dying plant parts and decomposition processes involving organic matter. In some cases, phosphates are added to water by water companies or get into water through their use in agriculture. As long as the amount of phosphate is reduced to a low level by the existing plants, there is a dynamic balance between "supply and demand". Only the uncontrolled increase in the phosphate level may create problems, such as strong algae growth. Phosphates are considered a limiting factor for the growth of thread algae. The right phosphate value is particularly important for healthy, abundant plant growth. This means that higher values are required in a heavily planted aquarium than in a less heavily planted aquarium. In a community aquarium with few plants and many fish, aim for a fairly low value, because the usually higher animal population and therefore larger food quantities often results in quite a high value anyway, although this can be reduced by regular and large scale water changes. In this case, the value should not exceed 0.05–0.1 mg/l. In heavily planted aquariums, things may be different and fertiliser may have to be added to achieve the ideal value of 0.1 to 0.3 mg/l. It is important that the values are not too high, to prevent unwanted algae growth.

 

Chlorine

In some cases, water suppliers add chlorine to the tap water for disinfection. Chlorine cannot be tolerated by aquarium fish and other aquarium inhabitants even in very small quantities and must be removed from the water before it is added to the aquarium.

 

Iron content

Iron is essential for good plant growth. However, concentrations of 0.1 to 0.2 mg/l are usually more than sufficient. Higher dosages often promote the formation of red algae, such as brush and beard algae.

 

Oxygen content

All aquarium inhabitants and plants need oxygen, so this is a very important factor. In well planted aquariums, the plants produce enough oxygen during the day. However, it may be necessary to aerate the aquarium at night, as plants and fish also need oxygen at night. It is also important to ensure good gas exchange in the aquarium.

Need inspiration?

We have put together a gallery of creative aquarium scapes for you.

 

Inspirations for your dream aquarium
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