The process involved in the breakdown or the mineralization of organic matter in the water (feed and plant debris, fish excrement) follows the stages protein - ammonium - nitrite - nitrate. Certain bacteria are responsible for this process. Measuring the intermediate stages ammonium, nitrite and nitrate allows certain conclusions to be made about the “function” of the system “aquarium”. Normally, ammonium and nitrite should not be allowed to enrich concentrations of above 0.2 mg/l (ppm). If they do, the bacterial balance may be disturbed. Many of the medications used to treat fish diseases can damage beneficial cleansing bacteria, leading to an increase in nitrite levels. As a rule, nitrite is not found in measurable amounts in a well-maintained aquarium with an efficient biological filter. Like ammonia, nitrite is highly toxic for fish; depending on the sensitivity of the fish species, concentrations between 0.5 and 1 mg/l (ppm) may be lethal.
The process involved in the breakdown or the mineralization of organic matter in the aquarium (feed and plant debris, fish excretions) follows the stages proteins - ammonium - nitrite - nitrate. Certain bacteria are responsible for this process. Measuring the intermediate stages ammonium, nitrite and nitrate allows certain conclusions about the function of the “aquarium” or “pond” system. Normally, ammonium and nitrite should not be allowed to enrich above concentrations of 0.2 mg/litre (ppm). If they do, the bacteria balance may be disturbed. A continuous increase in the nitrate content of the aquarium, accompanied by a low or undetectable ammonium and nitrite content, is characteristic of a well-functioning bacteria balance. Nitrate is the end product of mineralization in the aquarium, and it is non-toxic to fish even in relatively high concentrations. However, it has a detrimental effect on plant growth and on the well-being of some species of fish. If phosphate is present in the water in addition to nitrate, levels of nitrate which are too high promote the growth of unwanted algae. This is why the nitrate content of the water should be kept below 50 mg/litre (ppm).
The well-being of fish, invertebrates and the
growth of aquatic plants depend to a large extent
on the pH level being kept as constant as possible.
Many substances dissolved in water are also liable
to changes caused by the pH level. Fluctuations in
the pH level, in particular, ought to be avoided. The
pH level most conducive for keeping the majority
of freshwater fish and plants is in the neutral range
Depending on origin and consistency of the subsoil, water may contain varying quantities of alkaline earth salts. Owing to the effects of CO2, a large proportion of these salts is represented by hydrogen carbonates. By definition, the proportion of calcium and magnesium salts represented as carbonate is described as carbonate hardness. As a rule, the carbonate hardness is below the total hardness value. In certain exceptional cases (e.g. the East African lakes) the carbonate hardness can be higher than the total hardness. Most freshwater fish and plants in an aquarium thrive well at a carbonate hardness of roughly between 3 and 15°d. For successful CO2 fertilization, the carbonate hardness should not fall below 4 to 5°d.
The well-being of fish, invertebrates and the growth of aquatic plants depend to a large extent on the pH level being kept as constant as possible. Many substances dissolved in water are also liable to changes caused by the pH level. Fluctuations in the pH level, in particular, ought to be avoided. The pH level most conducive for keeping the majority of freshwater fish and plants is in the neutral range around 7.
The water authorities add chlorine to the tap water to disinfect it and make it drinkable. However chlorine is harmful to gills and mucous membranes of the fish. And chlorine is not tolerated by invertebrates either. For this reason you need to check whether tap water contains chlorine BEFORE it gets into the aquarium. As soon as chlorine is present, a water conditioner, such as JBL Biotopol or JBL Biotopol C will help to neutralize the chlorine. For pond water JBL BiotoPond has been developed to treat the water and to remove the chlorine. If there is no living being present inside the chlorinated water the water also can be aerated with an air stone to expel the volatile chlorine gas (which takes about 24 hrs). Always check your tap water for the presence of chlorine before you fill it into your aquarium or pond and remove the chlorine, if needed, with the appropriate water conditioner.
Carbon dioxide (CO2) is the most important plant nutrient. Aquarium water usually has values between 2 and 4 mg/l if no carbon dioxide is added. However, a CO2 concentration between 15 and 30 mg/l is recommended, with 20 - 25 mg/l having proven to be optimum levels. This level is not harmful to fish whilst at the same time promoting luxuriant plant growth. Therefore, gradually adjust your CO2 fertiliser system until this level is attained. The amount of CO2 which needs to be added to your CO2 fertiliser system to achieve this value depends on various factors. These factors include water agitation and the intensity of illumination (more light causes plants to grow faster, thereby increasing the required CO2) in addition to direct consumption by plants. Thus the correct dose must be determined individually for each aquarium. You can find out more on this by reading the instructions for use of your CO2 fertiliser system. Tanks with few or no plants such as those preferred to keep fish from Lake Malawi or Lake Tanganyika do not need to be supplied with additional CO2.
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