For some reason, it so happens that in the literature and on many Internet resources, when the question of bacteria and biofilters in an aquarium is raised, first of all they write about nitrifying bacteria. Yes, these bacteria play a key role in the conversion of toxic ammonia / ammonium to nitrates, and this is especially important at the stage of launching a new aquarium, in the first month or two. However, these bacteria make up only a small fraction of the microorganisms in the aquarium, and the conversion of ammonium into nitrate is just one function of the many bacteria. On most bacteria, many aquarists have no idea. This article describes the types and functions of the most important representatives of the microflora of aquatic environments.
What is a biofilter for an aquarium?
In fact, bacteria are a biofilter. It is a mistake to assume that some special filter fillers can perform the function of a biofilter. Until the bacteria settle on the surface of the filler, such a filter cannot be called a biofilter. Without bacteria, such filters can only be mechanical, which collect small particles. Moreover, bacteria do not care on what surface to settle. They multiply on any safe surfaces. It can be not only a filter filler, but also a soil and even plants. If a lot of plants, they form a large surface. Therefore, the whole aquarium is a biofilter.
To understand how the micro world works in an aquarium, you need to abandon the idea that bacteria are a substance that can be added to an aquarium or a filter and how much you add it, as much as it will be in an aquarium. You need to know two things:
1) Almost all the bacteria that are needed in the aquarium, there is in it;
2) Bacteria multiply very quickly from a microscopic colony to millions.
Accordingly, it is not always necessary to add bacteria to the aquarium. After all, they are with a very high probability in it already. They are around us, in the air, in the water, on the surfaces. And you need to really try not to run the bacteria in the aquarium. Then the question arises – what is contained in all the preparations that are offered on the aquarium market? As a rule, these preparations contain food for bacteria, some enzymes that stimulate the growth of bacteria and cysts (passive state) of the bacteria themselves. The addition of these drugs creates favorable conditions for the development of bacteria, which, as a rule, are already in the aquarium. Among them is the AQUAYER Biostarter preparation, which contains nourishment for bacteria in the aquarium and cysts of different species of bacteria themselves.
Now it is clear that it is important not to place the bacteria in an aquarium, but to create conditions for their reproduction, to give them food. It is the food for bacteria that is key in understanding the biobalance in an aquarium. And depending on what kind of food is present in certain zones of the aquarium, the corresponding types of bacteria settle in these zones, each of which performs its own function.
The main types of bacteria in the aquarium and their functions
Up to 60% of bacteria in an aquarium are Actinobacteria. These bacteria decompose organic polymers such as chitin (from invertebrates) and cellulose (from plants) to simpler organic compounds. In an aquarium, actinobacteria form the sludge that plants need. Most actinobacteria are aerobic, that is, they need oxygen for their vital functions. Therefore, these bacteria settle in areas with good circulation of water: the upper layers of the soil, the filter (external or internal), the surface of plants, glasses. The products of vital activity of these bacteria include organic substances responsible for the smell of chernozem and what some experienced aquarists call the "smell of a healthy aquarium."
10-20% of bacteria in an aquarium are Betaproteobacteria, which also include nitrifying bacteria. Among these bacteria are aerobes and facultative anaerobes (they can use oxygen, and they can do without it). This type of bacteria plays an important role in the nitrogen cycle, transforming ammonium into nitrite and then into nitrate.
About 10% of the bacteria in an aquarium are anaerobes, which can not get oxygen from gaseous oxygen, but break down molecules that contain oxygen. In an aquarium, these bacteria live in anaerobic zones, usually the lower layers of the soil, where little oxygen enters. Among these bacteria the most interesting are Paracoccus denitrificans, because they are responsible for a number of biochemical processes in the aquarium. First of all, these bacteria can reduce the level of nitrates in an aquarium, turning it into gaseous nitrogen. This process is called denitrification. It is in the process of denitrification that these bacteria receive oxygen:
The ability of these bacteria to reduce the concentration of nitrates is actively used in marine and freshwater aquarium hobby aquarism. To speed up denitrification in a marine aquarium, you can use none other than regular vodka as a top dressing. Bacteria consume ethanol as a carbon source, and nitrate is consumed for anaerobic respiration. At the same time, the level of phosphates is also reduced, since bacteria are necessary for phosphates as a building material for cells. Without adding anything to the plant aquarium, these bacteria, although insignificantly, will reduce nitrates and phosphates if conditions are favorable. After all, the source of carbon for them can be carbohydrates from the cells of dead leaves of aquarium plants. For freshwater aquariums without plants, for example, with cichlids and other large fish, AQUAYER NO3 minus can be used as a stimulation of denitrification. With a certain diet, these bacteria can even increase carbonate hardness. An important useful property of these bacteria is their omnivorous nature. As a carbon source, they can consume not only alcohols and carbohydrates, but many other organic compounds, thereby purifying water. This property is used in the process of wastewater treatment.
A simple experiment – "biovzryv" in the aquarium.
In order to assess how the bacteria in your tank can affect the balance of elements in the tank, you can experiment with sugar. 1 teaspoon of sugar per 100 liters of aquarium water will dramatically increase the population of virtually all types of bacteria in an aquarium. Sugar is the easiest carbon source to digest by bacteria. As a result of this experiment, a series of processes will take place in the aquarium during the week:
1) Aerobic bacteria will reduce the level of oxygen and you may notice a lack of oxygen in fish.
2) Aerobic nitrifying agents will reduce ammonium and nitrite levels if they are present in water.
3) Anaerobic bacteria will reduce the level of nitrates and phosphates.
4) The concentration of CO2 will slightly increase as a product of sugar processing by bacteria.
At the next stage, the bacteria, as they rapidly increase the population, will also rapidly increase it, because they have already eaten sugar. At the same time, the water will be saturated with the products of their decay (organic matter), which over time is processed again by bacteria. This method is used to reduce the level of nitrates and phosphates in cichlids. And in order not to upset the balance and not to introduce life into the aquarium into such stress, sugar is added in smaller portions – not one-time 1 teaspoon per week, but breaking it into 7 days.
How not to harm the bacteria in the aquarium and what to do if it was done.
What can reduce the population of bacteria and disrupt the balance in an aquarium?
1) Lack of oxygen. Even if it is a plant aquarium, you need to understand that plants do not always produce a lot of oxygen. If they are deprived of food, then photosynthesis slows down dramatically. As a result, the level of dissolved oxygen in water can sharply decrease. As oxygen levels decline, the aerobic bacteria population will decrease. This in turn will lead to the accumulation of those substances that served as food for these bacteria.
The concentration of oxygen in the plant aquarium fluctuates during the day. At 25 o C, the water is saturated with oxygen up to 8 mg / l, but in aquariums with a large number of plants and their active photosynthesis, they can become oversaturated and reach 10 mg / l by the evening. At night, the oxygen concentration drops to 4–5 mg / l, even when aeration is switched on, since air contains only 23% of oxygen, and oxygen consumption at night increases. Avoid falling oxygen concentration up to 2 mg / l. The slightest excitement on the surface of the water provides support for the concentration of oxygen overnight at a level not lower than 4 mg / l.
2) CO2 overdose and lower pH. Acidic water is an antiseptic, the lower the pH, the higher its antiseptic properties. Not all bacteria like this, so it’s best to ensure that the pH is not below 6.0.
3) The use of disinfectants. Unfortunately, preparations that aquarists treat fish or fight against algae are disinfectants and they severely disrupt biofiltration in the aquarium. After their application, it is better to conduct a recovery course using biostarters that have already been mentioned in the article.
Competition of bacteria, algae and plants.
Not only plants and algae are competitors. Bacteria consume the same macro and microelements as plants with algae. Therefore, in an aquarium with a working biofilter, problems with algae are less common. Bacteria with plants simply deplete the algae. If, for some reason, the plants stopped growing, or the bacterial population was reduced, for example, by the action of disinfectors, then free food for the algae appears in the aquarium. In general, if one of these three biobalance participants dramatically reduces their biomass, the other participants can accelerate growth.