CO2 System Basics

The two basic requirements for healthy aquarium plants are light and proper carbon dioxide (CO2) levels. Through a process called "photosynthesis," aquarium plants use light energy and CO2 to produce food necessary for lush growth. As plants develop, they use up their existing supply of carbon dioxide. Installing a CO2 system is essential to prevent low CO2 levels and to maintain active plant growth. These systems are available in three basic styles to ensure a healthy environment for planted aquariums of all sizes.

Example of Manual Systems:

• Turbo CO₂ Bio-System

Semi-automatic CO₂ Systems
Semi-automatic CO₂ systems involve a bit more effort to install initially, but are timer-operated to help simplify CO₂ injection. A CO₂ canister supplies carbon dioxide and the amount of CO₂ entering the aquarium is controlled by a series of components, including a pressure regulator with solenoid, a bubble counter, and a CO₂ diffuser. The timer-operated solenoid opens during a set period of time (i.e. when the lights are on) to supply plants with carbon dioxide. These systems are perfect for mid-size and larger planted aquariums that have a greater demand for CO₂.

Examples of Semi-automatic Systems:

• Drs. Foster & Smith Semi-Automatic CO₂ System
• Fluval Pressurized CO₂ Kit

Do I need a CO2 system for my planted aquarium? CO2 supplementation is usually contingent upon light intensity. In general, heavily planted aquariums with high output light fixtures will require a CO2 system to keep up with the greater plant demand for carbon dioxide.

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• Drs. Foster & Smith Deluxe Fully-Automatic CO₂ System

No matter which style of CO₂ system you employ, it is important to routinely monitor aquarium pH and CO₂ levels. Excess CO₂ can create conditions harmful to fish including low oxygen levels and drops in aquarium pH.