CO2 - what is it? The use of CO2 in the aquarium. CO2 supply system

CO2 - what is it? The use of CO2 in the aquarium. CO2 supply system
CO2 - what is it? The use of CO2 in the aquarium. CO2 supply system

Sooner or later, every serious aquarist faces the question of supplying the aquarium with CO2. And for good reason. Why do aquarium plants need it?

So, CO2 - what is it? We all know that aquatic plants feed primarily on carbon dioxide dissolved in water. This is CO2. In nature, plants get it from the reservoir in which they grow. Since the volume of water in natural reservoirs is very large, its concentration in them is usually constant. But the same cannot be said about aquariums.

co2 what is it

Plants quickly use up all the CO2 gas from the aquarium water, and its concentration will not be restored by itself, because the aquarium is a closed system. Even the fish contained in it will not be able to make up for the lack of CO2, as they exhale such a meager proportion that it will never be enough for plants. And as a result, aquarium plants stop growing.

In addition to the fact that plants stop growing due to a lack of CO2, water in which its content is low hasincreased hardness (pH), which is detrimental to them. Even inexperienced aquarists have probably noticed that after adding plants, tap water becomes harder than it was in an empty aquarium. This is due to the fact that carbon dioxide contributes to the appearance of carbonic acid in water, and it lowers hardness. That is, it is important to understand: the less CO2 in the water, the higher its pH.

How to help the plants in the aquarium?

There are several ways to solve the issue of supplying plants with CO2. You can install a special cylinder and appropriate equipment, or you can go the other way and try to do everything you need with your own hands. Many people prefer this way. And it is clear why - it is much more interesting and pleasant to solve the problem on your own, without resorting to the help of purchased equipment.

co2 gas analyzer

The only thing worth paying attention to is the result. Not knowing how everything works in the aquarium, you should not go there and change and redo something, so as not to be upset later. The important thing here is not participation, but understanding what you are doing.

Nowadays, more and more aquarists are engaged in breeding aquatic plants and independently solve problems with a lack of carbon dioxide in the water. To some extent, such a scale may well negate all the results of the fight against harmful emissions from enterprises and cars, because home-made aquarium devices have become necessary and very fashionable, and their volumes are sometimes quite large. Of course, this is a figurative comparison, but there is some truth in these fears.

So, CO2 gas - what is it? How to deal with carbon dioxide in our aquarium and how to produce it inexpensively and in sufficient quantities? But it is quite realistic to make such a system yourself and refill it 5-7 times a year.

What do aquarium plants need?

Once again, let's remember what CO2 is and why plants need it in an aquarium. CO2 for an aquarium is a source of carbon that plants need, like food for humans. Plants consume it in the light, but in the dark they need oxygen no less. This is the first problem beginner aquarists face.

If you forget about this, then at night the aquarium will start to freeze. Even if there is no obvious death of the flora, the plants will simply stop growing normally, and this will make all our efforts meaningless.

In other words, there must be constant diffusion (aeration) in the aquarium. And oxygen should be enough for the dark half of the day. Usually there is a lot of it at the beginning of the day, but plants, like fish breathing it, “choose” it pretty quickly. In such a situation, CO2 will not only not be able to help, but will easily exacerbate the problem.

do-it-yourself CO2 for an aquarium

No less common is something else. Beginners in the aquarium business, seeing how their seemingly unpretentious Vallisneria or easy-to-care Riccia with hygrophila completely refuse to grow, they begin to play tricks with CO2 and experiment in the hope of improvement. And the point is not at all an insufficient amount of carbon dioxide or light. These easy-to-keep plants thrive well withless light and less carbonated water. It turns out that simply either the plants were bought "on the verge of death", or the soil is too poor or the water is new, not yet settled.

Which is more important - light, fertilizer or CO2?

The formula for success is simple: CO2 for the aquarium, nutrients and light. And you need to treat it not fictitiously, but with all respect, because all its components are equally important for plant life. If you "disperse" the system in the direction of one of them, without taking into account the other two, then quite quickly and inevitably you will encounter the manifestation of Liebig's law instead of admiring the strong and he althy flora in your artificial reservoir. This is the so-called swing effect. Moreover, the more the system is overclocked, the more intervention will be required, and in the meantime, the plants “get tired and yearn.”

As a result, instead of vigorous greenery in the aquarium, everything gradually fades, and then some of the plantings die. Or the water will begin to fill with algae if the plants cannot “digest” our “broth”.

Factors affecting the composition of water in an aquarium

It's interesting that when you think about CO2, oxygen, light and nutrients, you often forget about temperature. And it is the main regulator of aquarium photosynthesis. Not light and not CO2, as it might seem. Botanists are well aware of this, but "aquarium researchers" forget this fact quite often.

co2 for aquarium

The regulatory role of such waves as infrared reflects precisely this function. Maybe,this is due to the fact that in the technologies used for manufacturing light sources used for aquariums, remembering the temperature is unprofitable. Therefore, they pretend that it is not important.

What can any aquarium do without?

Aquarium can do without fashionable and glamorous excesses. And not only can, but also safely manages. The main thing is to balance knowledge in the system and cause-and-effect relationships obtained through research. If the system is already in equilibrium, then it no longer needs to be touched! And don't try to fix something that already works properly.

Nevertheless, if the aquarium tank is too densely planted with plants, then even with good lighting, they may not have enough CO2. This is especially true for slightly alkaline hard water. If both species that can absorb only unoccupied carbon dioxide are combined (these are all types of mosses, many grasses that grow only in acidic and soft water, lobelia), and eurion and stenoion species that are able to extract carbon from carbonates (and this is Vallisneria, elodea, echinodorus, etc.), then the concentration of CO2 will be especially low.

CO2 concentration

Cure this is not at all difficult, as it is enough just to populate the aquarium with more fish. In those aquariums in which everything is normal with the ecology, and with a dense population of living creatures, plants do not experience a lack of carbon dioxide even with fairly powerful light. But in any case, an additional dose of CO2 will not be superfluous for such a reservoir.

We have looked at the role of CO2 in detail. What it is, now, too, is probably clear.It remains to learn how to make it at home.

Bash method of supplying the aquarium with carbon dioxide

To enrich the aquarium with carbon dioxide, the easiest way is to use ordinary mash. However, she wanders unsteadily. Initially, there will be an excess of gas that will escape, create a greenhouse effect, or create an excess concentration of CO2 in the water. Then its production rate will drop sharply.

Disadvantages of the mash method

There are only two of them:

  • The need for too frequent recharges (1, 5-3 weeks).
  • Difficulty in monitoring the operation of the system during the day.

However, this does not mean that CO2 supply to the aquarium is not available to you, as these shortcomings are easily solved by using a tank system. True, it has a rather high price, and besides the purchase, it still needs to be professionally configured.

Let's consider one of the recipes for using such a brew. Its advantage is that fermentation takes place very evenly and for a long time (3-4 months). Of course, there is nothing new in science, more gas will not come out of the same amount of matter, but the aquarium receives the required amount of CO2 evenly and slowly. For those who need a large amount of carbon dioxide, this recipe will by no means work, they definitely need a CO2 tank. In principle, no mash is suitable for stable high concentrations. But it copes quite satisfactorily with the task of supplying carbon dioxide to an average aquarium with a dense "population", nutrient soil and good illumination, if ineuryion and stenoionic species coexist in its hard water.

How to make a CO2 production system for an aquarium with your own hands

We use a plastic container with a volume of 1, 5 and 2 liters. In each case, the size of the containers may vary, depending on the volume of the aquarium and the amount of carbon dioxide needed.

co2 bottle

1. Pour the ingredients into the container: 5-6 tablespoons (with a slide) of sugar, one tablespoon of soda and 2-3 tablespoons of starch (also with a slide).

2. Pour 1.5-2 cups of water, as seen in the photo.

supply of CO2 to the aquarium

3. We send everything to the water bath.

CO2 supply system

Important: there must be water in the pan almost to the level of the liquid in the bottles, otherwise the composition at the bottom will not become thick, but will remain liquid on top.

4. Cook until the consistency of thick jelly, that is, until ready. You need to get a very thick mixture. If you knock over the bottle, then it should almost not drain.

co2 density

4. Cool the resulting mixture.

While the bottles are cooling, we are making tight and reliable caps with neat pipe fittings. After all, CO2 - what is it? This is a gas, which means that the sealing must be very thorough. It is convenient to use fittings for the VAZ brake system (about 12 rubles / pair in auto parts stores). We will need two such fittings, gaskets and washers for 8 (about 40 rubles / a pair of sets in OBI), as well as a pair of nuts for 8.

co2 gas

Knife andwith a heated nail, you need to make a hole, then drive the fitting into it with the thread down (thread inside the bottle). Above through the washer, and below according to the scheme: gasket / washer / nut.

co2 in water

It makes no sense to use various adhesives for sealing, since they will not provide the required protection. But the cover made according to the described scheme will securely hold the tube, while the entire CO2 supply system will turn out to be quite resistant to manipulation and recharging.

co2 what is it

After the bottles have cooled down, you need to add a teaspoon of yeast (can be dry) to our jelly, before thoroughly mixing them in water. For example, in a glass or glass.

Put the bottles prepared in this way in place, carefully connect and do not touch them for 3-4 months. Carbon dioxide is released evenly and slowly, and if low-flow bell-type reactors are used, then the whole process will be easily controlled visually. When the level in the bottles drops below the middle, it's time to refill them.

Reloading is simple. The fermented mixture again turns into a liquid and pours out, a new one is laid in its place, and you again get CO2 for the aquarium. A do-it-yourself device based on plastic bottles will easily survive many such recharges without losing its qualities. Gas is supplied around the clock.

Types of reactors for aquariums

  • "Bell" is any reactor made on the principle of an inverted glass. Other types of reactors are not recommendeddissolve the mash, since the process of carbon dioxide release will become uncontrollable, and the density of CO2 will become uneven.
  • The simplest reactor of this type is a disposable syringe attached to the aquarium wall with a suction cup. Converted bird drinkers also look quite aesthetically pleasing, and besides, they are inexpensive. There are many options: from a plastic cup turned upside down to complex designs.

The efficiency of any reactor directly depends on the "contact spot" - the size of the area of ​​contact between water and gas. Laffart advises for every 100 liters of water (hardness 10 grams) to make a dissolution area of ​​30 square meters. cm. This is not so much - just something 5x6 cm.

co2 gas analyzer

So, there is a dilemma - to make a large reactor, or a small one, in which the dissolution process will be much better than in a large one.

This effect can be obtained by directing part of the water through a thin tube from the filter under the "flute" to obtain a "fountain" inside the reactor. If such a flow is organized, for example, in a reactor from a syringe (20 cubic meters), then the dissolution will improve several times, and the CO2 concentration will be uniform. And this is tantamount to using a bell-type reactor, which has more bulky dimensions.

Cylinder method for CO2 enrichment

For large aquariums, the best method for enriching water with carbon dioxide is the balloon installation method. Such a system consists of a cylinder and a control system, i.e. a reducer, a valve, fittings, a coil with connectors, an air throttle and a blocknutrition. It is easy to assemble such an installation yourself, but it is easier to buy a ready-made one in a store, however, it will cost several times more.

do-it-yourself CO2 for an aquarium

Advantages and disadvantages of the balloon method


  • CO2 production stability.
  • A large amount of gas produced.
  • Economy.
  • If you connect a pH controller and a CO2 gas analyzer, you can fully automate the process.


  • High price.
  • Difficulty of self-assembly.
  • High pressure cylinder required.

In conclusion

Returning to the choice of CO2 generator, we should also mention another type - chemical. Unlike a mash-powered generator, a chemical one uses the reaction of an acid with carbonates. Like the mash method, such chemical reactors are suitable for small aquariums - up to 100 liters in size. In addition to everything mentioned in this article, it is possible to purchase a CO2 gas analyzer in the store and use it to constantly monitor the state of the water in your artificial reservoir.

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