The Importance of Carbon Dioxide in Planted Tanks

Cultivating a thriving planted tank can be a challenge if you do not understand the requirements of live plants. Though some live plants can survive if you simply root them in gravel, if you plan to cultivate a heavily planted tank this is unlikely to be sufficient. Live plants require certain substrate to provide the nutrients they need to grow. In addition to these nutrients, aquarium plants also require plenty of light and carbon dioxide (CO₂). Without adequate carbon dioxide levels in the tank, your plants are unlikely to thrive.

The Role of Aquarium Plants

In the freshwater aquarium, live plants do more than just improve the aesthetics of your tank. They also provide fish with a place to hide and even provide a supplemental food source for plant-eating fish. More importantly, however, live plants convert carbon dioxide (the product of cellular respiration) into the oxygen your fish need. If the oxygen levels in your tank drop too low, your fish could become stressed or even experience physical symptoms of oxygen deprivation. As an indication that the oxygen levels in your tank are too low, you may see your fish gasping at the surface or hanging out near the filter return. If your fish are displaying these signs, it may already be too late to remedy the problem – your best bet is to add some live plants to the tank to prevent low oxygen levels from becoming an issue in the first place.

Lighting and Carbon Dioxide

These are the two basic requirements for maintaining a healthy planted tank. Aquarium plants are photosynthetic organisms which means that they use light as energy to fuel biological processes. In addition to tank lighting, plants also require carbon dioxide to produce the food they need to grow – a byproduct of this process is oxygen. As aquarium plants grow, they use up the existing supply of carbon dioxide in the tank – if you have a heavily planted tank you may need to supplement the CO₂ supply to keep your plants healthy. There are several different options for carbon dioxide supplementation.

CO₂ Supplementation

The three main types of CO₂ supplementation systems are manual, semi-automatic and automatic. Manuals systems involve yeast fermentation and they are generally inexpensive and easy to use. This kind of system typically consists of a bottle containing yeast and sugar – as the yeast ferments the sugar, carbon dioxide is produced which is then released into the tank via a hose attached to the bottle. Though easy to use, these units must be turned on and off by hand.

Semi-automatic CO₂ systems may require a little more set-up but they can be operated by timer once they are installed. This type of system consists of a CO₂ cannister which releases carbon dioxide into the tank at a level controlled by a pressure regulator. This type of unit can be configured to turn on when your aquarium lights come on and to turn off when the lights turn off. This is an important feature because if you add too much CO₂ to the tank without also providing adequate lighting, your live plants won’t have the energy they need to process the extra CO_2. These units are ideal for mid-sized planted tanks.

The third type of CO₂ supplementation system is an automatic system. These devices are very similar to semi-automatic systems but they also include a pH probe and controller. Because excess CO₂ can affect the pH of an aquarium, this is a very important feature. When the pH probe detects that the pH of the tank is falling below the preferred level, it automatically shuts off the supply of CO_2. These systems can be used in planted tanks of all sizes but they are most beneficial in large or heavily planted tanks.

Other Tips for Planted Tanks

Remember, in the same way that your aquarium fish require high water quality in order to thrive, so do your live plants. In addition to providing adequate lighting and CO₂ levels, you also need to make sure the water parameters in your tank remain stable. It is recommended that you create a maintenance schedule so you remember to complete routine maintenance tasks including water changes and water tests on a regular basis. You should be prepared to perform small water changes once a week and should test the water in your tank at the same time. Replace your filter media once a month and perform routine checks to make sure all of your tank equipment is fully operational.

If it sounds like maintaining a planted tank is a lot of work, don’t be discouraged. Start off small with just a few aquarium plants and see how they adjust to the conditions in your aquarium. Over time you can add more live plants to create a lushly planted tank environment. Keep in mind that a heavily planted tank requires a high-powered lighting system and you may also need to look into CO₂ supplementation at some point.