Carbon dioxide fertilization

In most planted aquariums, C02 fertilization is essential for good plant health and is often the limiting factor in overall growth. Without adequate levels of C02, plants cannot photosynthesize effectively and therefore cannot produce the energy needed to perform basic physiological functions. There are several ways of introducing C02 into the aquarium. It is created naturally through fish and plant respiration, but mostly by bacteria as they break down organic matter. Many soil-based and established substrates will continually release C02, which can be used by aquatic plants. However, the quantities produced by these processes are minimal and would not be enough for heavily planted tanks. This is why additional fertilization is essential. Furthermore, the air/water exchange in an aquarium continually releases a large quantity of C02 into the atmosphere that must be replaced.

Because C02 is a gas, it is not possible to introduce it into the aquarium through conventional means, such as by way of liquid or substrate fertilizers. Various devices designed to introduce C02 into the aquarium are available for hobbyists and these include those using tablets that slowly release C02, slow-release chemical reactors, and pressurized C02 cylinders that can be adjusted and set by timers. All these systems introduce C02 gas directly into the aquarium water. The aim is to keep the gas in contact with the water long enough for it to be available for plants to absorb.

Carbonator Aquarium

Above: In this chemical-based system, a reaction between two compounds in a plastic container gradually releases C02, which is absorbed by the water. These aquarium carbonators are effective but inexpensive and simple to install in the tank.

Growing Aquarium Plants Outside

Simple methods of C02 fertilization

Above: In this chemical-based system, a reaction between two compounds in a plastic container gradually releases C02, which is absorbed by the water. These aquarium carbonators are effective but inexpensive and simple to install in the tank.

Tablets and powders that produce C02 when added to water provide the working principle for a range of simple C02 fertilization techniques.

A chemical reaction is activated inside this — disposable container, which releases C02 over a month at a steady rate.

C02 collects under the "bell" and is absorbed into the water.

Slow-release CO? tablets

Slow-release C02 and potassium tablets

Slow-release C02 and manganese tablets

This powder is used to start the reaction inside the unit.

These tablets slowly dissolve, producing C02 Replace them when fully dissolved.

How C02 cylinder fertilization works The aquarium lights provide an energy source for photosynthesis.

Connectors and valves are standard

Aquarium Plant Photosynthesis

How C02 cylinder fertilization works The aquarium lights provide an energy source for photosynthesis.

This valve closes when the lights are off, preventing the release of C02 gas.

Carbon Dioxide Fertilization

The bubble counter allows tiny C02

bubbles to travel slowly upward, allowing maximum time for the gas to diffuse into the water.

Carbon Dioxide Aquarium Plants

fit and suitable for all systems.

Right: Carbon dioxide gas enters at the bottom of this diffuser, or bubble counter. After a running-in period of about 48 hours, the bubbles stabilize and become smaller as they rise and release C02 gas into the water.

This valve closes when the lights are off, preventing the release of C02 gas.

Cylinder systems can be connected to a light timer so that gas is only released when the lights are switched on. Plants have no use for C02 at night and an excess at night can harm the aquarium.

The cylinder contains compressed C02 gas, which is released at a controlled rate via a regulator. The two dials indicate the release rate and the pressure of the gas in the cylinder, which reflects the amount of gas remaining.

Right: Cylinders containing compressed C02 are ideal for larger aquariums and long-term C02 fertilization. The gas produced is sent to a bubble counter, where it is kept in contact with the water for an extended time.

The bubble counter allows tiny C02

bubbles to travel slowly upward, allowing maximum time for the gas to diffuse into the water.

fit and suitable for all systems.

Right: Carbon dioxide gas enters at the bottom of this diffuser, or bubble counter. After a running-in period of about 48 hours, the bubbles stabilize and become smaller as they rise and release C02 gas into the water.

Connectors and valves are standard

Macronutrients carbon

These nutrients are used in the greatest quantity by aquarium plants and are vital to many plant functions. Without them, plants would be unable to grow, repair, or maintain healthy tissue.

Carbon Dioxide Fertilization

Hydrogen

Hydrogen is used as water (H20), mainly as a structural component to fill cells, provide support, and as a means of transporting properties throughout the plant. Clearly, hydrogen as H20 is easily available in the aquarium and there is no need to add more.

Calcium

Calcium is a vital element used by plants in the formation of cell wall structure and to maintain cell permeability. It may also activate some enzymes. Although calcium is present in sufficient quantities in most water supplies, it may be deficient if only rainwater or reverse osmosis water is used in the aquarium. Many gravel-based substrates (other than quartz substrates) contain some calcium and this, combined with at least a partial use of tap water, should provide sufficient quantities of calcium for the majority of plants. In most cases, calcium should not be added artificially to the aquarium, as an excess will limit the availability of other nutrients and raise water hardness. However, many plants from naturally hardwater areas will require higher levels of calcium. Due to the fact that it is readily available in their natural environment, these "hardwater" plants are not evolved to collect calcium efficiently in low-level conditions.

Calcium is essential for basic plant structure and particularly important for plants from hardwater areas. This Crinum natans will thrive in medium water hardness levels.

Carbon is used by all living organisms as a basic structural "building block" and makes up 40-50% of a plant's dry biological mass. In terms of quantity, carbon is by far the most important nutrient. Plants obtain carbon from carbon dioxide (C02), which is broken down into oxygen (02) and carbon through the process of photosynthesis. Although plants need oxygen as well as carbon, the amount of oxygen required compared to carbon is minute, so the majority of oxygen is expelled as gas bubbles from the leaves.

C02 is a gas, so the amount present in a body of water is affected by the air/water exchange. If a body of water is highly agitated at the surface, then the air/water gas exchange is increased and the level of C02 in the water will rise or drop, depending on the level of C02 in the immediate atmosphere. For plants to obtain enough C02 from the water, the level of C02 needs to be much higher than normal atmospheric levels allow. This means that it must be introduced into the water from an internal source (i.e., not from the surrounding air). In nature and in the aquarium, C02 is introduced into the water as a result of the breakdown of organic waste by bacteria and by plant and animal respiration.

Plants can acquire the C02 they need by a number of methods, including direct uptake from the substrate through the roots, direct uptake from the water through leaves, "recycling" of respired C02, and through the breakdown of bicarbonates in the water. Although the concentration of C02 is highest in the substrate (due to the large amount of organic matter) it does not diffuse readily and therefore is not always available in large quantities in the immediate vicinity of the plant roots. The easiest way for plants to obtain C02 is directly from the surrounding water and through the leaves. In some aquariums, C02 levels are sufficient for good plant growth, although in most cases growth is limited by the amount of C02 present. Usually, it is necessary to introduce additional C02 to maximize photosynthesis and hence the amount of carbon available to the plants. There are several methods of introducing C02 to the water and these are discussed on pages 70-71.

Nitrogenous wastes produced by fish are a major source of nitrogen compounds in the aquarium. Plants absorbing -these can help to keep the water safe for animal life.

Magnesium

Magnesium is a vital macronutrient for all plants with a part to play in numerous important functions, and an important ingredient in chlorophyll. Magnesium is also used to activate enzymes that form vital fats, oils, and starch. Magnesium is a "hardwater" nutrient and often found in levels proportionate to calcium levels. However, levels of magnesium in tap water vary a great deal depending on local conditions, so it is difficult to know whether additional fertilization is needed. Water authorities can often provide readings of quantities in the local tap water and test kits are available to measure levels of magnesium. The ideal level of magnesium in a planted aquarium should be about 5-25 mg/liter, although many plants live outside this range in nature. In general, there is usually sufficient magnesium in tap water in hardwater areas. Using a nutrient-rich substrate additive or soil-like substrate should provide a constant release of magnesium into the water. Alternatively, you can use liquid fertilizers, which are especially recommended for softwater aquariums. Many liquid fertilizers contain magnesium sulphate (better known as Epsom salts), which is ideal, as it provides both magnesium and sulphur. Bear in mind that an excess of magnesium in the water will inhibit the uptake of other nutrients, particularly potassium. In fact, potassium deficiency is often due to an excess of magnesium.

Tap water from hardwater areas has high levels of mineral salts and is a good source of magnesium and calcium.

Co2 Fertilizion

Nitrogen

Nitrogen is one of the major nutrients required by all plants, both aquatic and terrestrial, for strong growth and good health. It is used mainly In the production of proteins and nucleic acids and makes up about 1-2% of a plant's dry weight. Plants do not take up nitrogen in its "raw" gas state (N?) but can obtain it in a number of forms, including ammonia (NH3), ammonium (NH4+), nitrite (N02~) and nitrate (N03~). Most plants take up nitrogen in the form of ammonium and nitrates, and although the preference varies according to species, ammonium is mainly preferred to nitrates. The main reason for this is that plants use ammonium to synthesize proteins, and if nitrogen is absorbed as nitrates, the plant must expend energy converting the nitrates back into ammonium. In the aquarium, ammonium is produced by fish in waste matter and as a result of the decomposition of organic materials. It is normally converted first into nitrites and then into nitrates by the bacteria in a biological filter. Many plants will take up ammonium before the filter bacteria are able to convert it, although the two are both in competition for the ammonium. However, do not be tempted to reduce the biological filtration with the aim of increasing the amount of ammonium available to plants. In soft, acidic water, ammonium is not dangerous to fish but in hard water with a pH above 7, ammonium is converted into ammonia, which is highly toxic to both fish and plants, making biological filtration even more important in hardwater aquariums.

Plants rely heavily on nitrates rather than ammonium as a source of nitrogen in hardwater aquariums. Although plants will often use nitrates only in quantity once the ammonium source is depleted, bear in mind that nitrates are a much safer source of nitrogen where fish are concerned, especially in harder water. Many liquid fertilizers contain nitrates as a nutrient ingredient, but it is important to keep a check on nitrate levels within the aquarium. In most cases, plants can obtain enough nitrogen from natural levels of nitrates produced as an end result of the biological filtration of aquarium waste (mainly from fish and, indirectly, fish food). Nitrate is easy to test for in the aquarium and many simple test kits are available for this purpose. Ideally, nitrate levels should be kept below 25 mg/liter. Many tropical aquarium fish can cope with levels higher than this, but in natural conditions plants rarely experience levels above 2 mg/liter, and levels above 30 mg/liter may be harmful.

Aquarium and Fish Care Tactics

Aquarium and Fish Care Tactics

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  • christin
    How co2 fertilization aquarium?
    6 years ago

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