CO2 in a plant aquarium for beginners

If you recently have a freshwater aquarium with live aquarium plants, or are just picking plants for your aquarium, then you have probably already read that there is a need of CO2 in a plant aquarium. If this topic is new to you, then read this article first. We will not delve deeply into this issue, but we will get acquainted with the terms, methods of introducing CO2 into an aquarium with live plants, or the so-called herbalist.

Why is CO2 in a plant aquarium needed ?

First, why introduce gas, which some consider to be harmful, into our aquarium? This is necessary in order for plants to grow and photosynthesis to take place.

What happens during photosynthesis? Plants absorb sunlight and use carbon dioxide (CO2) and water (H2O) to produce glucose (C6H12O6) and release oxygen (O2).

Therefore, for such an important process in plant cells as photosynthesis to take place, CO2 must be present in the plant environment.

The good news is that the water in the aquarium is always in a more or less balanced state and CO2 is always present in it, about 6-7 parts per million. This amount of carbon dioxide is enough to grow simple aquarium plants in low light conditions. However, when you start to increase the lighting in the aquarium to medium to high, the plants can completely deplete the CO2 in the water.

In this case, if you start to do additional CO2 injections, then very quickly make sure that with a sufficient amount of carbon dioxide, plant growth is noticeably accelerated. At the same time, plants grow healthier, and, of course, more beautiful in appearance.

In addition, due to the fact that the plants grow in full force, the likelihood of the appearance of algae is significantly reduced. Often times, aquarists use CO2 not only for healthy plant growth, but also to combat algae that invariably appear in strong light in an aquarium. And rightly so – applying enough CO2 will reduce or stop the growth of single-celled green pests.

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How to apply CO2 to the aquarium?

There are 2 general ways:

  1. DIY CO2 aquarium. In this case, a yeast starter culture is made in a bottle, which is better known among amateurs as “mash”. This is a very cheap but also much more time consuming method. This system can work very efficiently, especially in aquariums less than 100 liters. Of course, with experience you can learn how to create a DIY CO2 system for much larger tanks.
  2. Balloon system . This method is generally recommended for large aquariums and those looking for ease of use and automation. This method, however, includes equipment costs.

DIY CO2 system essentials (wash)

The basis for a do-it-yourself CO2 aquarium is the so-called reactor or wash: water, sugar and yeast mixed and sealed in an airtight vessel. Yeast is a breathing living organism (this is the opposite of photosynthesis). Yeast uses sugar to produce energy, water and CO2. CO2 is released as a gas and it is this by-product that our aquarium needs. Pressurized gas leaves the reactor and enters the aquarium.

A typical DIY system consists of a high pressure vessel (2 liter bottles in the example).

A mixture of yeast, sugar and water is placed in a “yeast generator” and sealed (there may be different mixes, recipes too, you can find recipes for homemade CO2 mixes on the Internet). There is a tube from the generator to the gas separator (you can use a tube from a dropper).

This system allows you to control the production of gas by the yeast and avoid leakage of both the mash into the aquarium and water into the mash. If you fill the separator with water, it can also serve as a bubble counter, so you can partly determine how much CO2 your system is producing: CO2 will bubble into the separator, and then, through the left pipe, enter the aquarium and dissipate.

To spray gas bubbles when feeding into the aquarium, a rowan branch is often used – passing through it, gas enters the aquarium in tiny bubbles.

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Benefits of using two generators:

  1. Sometimes one container is not enough for the volume of the aquarium in which you want to use the system. There is one good rule of thumb: 1 generator for every 35-75 liters of water.
  2. The second vessel allows maintaining the CO2 concentration at a constant level. One generator is enough, on average, for a week, but if you connect 2 and change them in turn, there is always one more recent than the other. When you mix yeast, sugar and water, a large amount of gas is produced at first, but over time the mixture starts to run out. Multiple mixtures ensure that one is fresh to maintain stability. This is very important that CO2 in a plant aquarium as too little CO2 injection often does more harm than good when it comes to algae growth. If you are not ready to regularly change your homemade CO2 mixes, or buy a ready-made pressurized system, it is best to skip adding carbon dioxide to your aquarium altogether.

Yeast generators are located on the left and right, in the middle of the gas separator. To the left is the gas pipeline to the aquarium. As you can see, the type of container for the wash is not fundamental, the main thing is that the vessel is tightly sealed, and then the gas will constantly flow into the aquarium through the system.

This version of the system is just great if you don’t want to spend a lot of money. Many people use home-made systems, and it will cost very cheaply.

If you don’t want to make mash every week or if you have a large aquarium

The CO2 cylinder supply system consists of a pressurized CO2 cylinder with a reducer (regulator) screwed in from the top, which allows CO2 to be supplied at a controlled rate. The pressurized balloon system is a great option for large aquariums or if you want a set and forget CO2 supply. How long this system will last depends on the size of the tank, the volume of the aquarium, the diffusion method.

On sale you can find disposable CO2 cylinders, which are simply thrown away after use, and reusable. When the gas in the refueled cylinder runs out, you only need to replenish its reserves for a small fee. Also, the balloon system is fully controlled, you can turn off or limit the supply of CO2.

You can turn off the feed at night, since plants need light for photosynthesis.

The main components of the CO2 supply system

CO2 bottle. What is important to pay attention to when buying a cylinder? If it is a refillable bottle, first find out where you can refill it. If it is an imported cylinder, there may be problems with filling. CO2 cylinders should be transported and stored only in an upright position. Another feature of cylinders is a threaded tap for connecting a reducer, it is better to make sure that you can get a suitable reducer, although an adapter can often be used.

Reducer. It is necessary to contain the gas pressure, it is selected to the cylinder.

CO2 solenoid valve. It controls the gas supply to the aquarium. You can control the supply with a timer, turn off at night and turn on with the lighting, or use a pH controller to supply CO2 depending on the pH.

Needle valve. A valve for fine adjustment of gas is not needed for special aquarium reducers.

Bubble counter. It is necessary for visual control of the gas supplied to the aquarium from a reducer or a needle valve.

Check valve. It is necessary to prevent the backflow of water from the aquarium to the reducer. If water gets into the reducer, needle valve, or solenoid valve, they may deteriorate.

CO2 hose. It is advisable to purchase a special hose for supplying gas to the aquarium.

Diffuser. Diffusers can be of a wide variety of options, but they all have one goal – the maximum dissolution of CO2 in water. This is achieved by reducing the size of gas bubbles, increasing the area of ​​contact between gas and water, and increasing the time of contact of gas with water.

How to control CO2 levels in your aquarium

CO2 in a plant aquarium,For aquarium plants, it is recommended that the CO2 level in the aquarium is maintained at an ideal of 20-40 ppm (parts per million). A lack of CO2 will lead to a shortage of it in plants, an excess to an excessive drop in pH with even more sad (for living inhabitants of the aquarium) consequences. There are 2 ways to control CO2 levels, although both are based on the fact that CO2 lowers the pH.

Method 1. This method requires tests to measure the pH and dKH (carbonate hardness) of water. These tests can be purchased at any specialty store, sometimes at a pet store. Below is a table in which you can determine the presence of CO2 in an aquarium.

Thus, CO2 in a plant aquarium, according to the table, if the tests showed pH = 6.8, dKH = 7, then CO2 is 34ppm, that is, the optimal value. Optimal, as you understand, the green zone.

Method 2. CO2 dropchecker is a water test, based, again, on determining the pH and carbonate hardness of water, but much easier to use. The water enters the dropchecker and is colored. The blue color of water indicates a lack of CO2, yellow about its excess, green about the optimal value.