What is CO2 tank?


Creating the perfect aquascape requires not just the right fish and plants, but also the perfect balance of nutrients and gases. One crucial element in this mix is carbon dioxide (CO2). This article aims to shed light on an integral component of maintaining adequate CO2 levels - the CO2 tank. But what is a CO2 tank?

co2 bottle

Understanding a CO2 Tank

A tank of CO2, commonly known as a CO2 tank or cylinder, is a storage vessel used to contain and transport CO2 in a pressurized form. These tanks come in different sizes to cater to a variety of needs, from small aquarium setups to larger aquascapes.

What is a CO2 Tank Used For?

So, what is a CO2 tank used for? In the world of aquascaping, CO2 tanks play an indispensable role in providing a steady supply of CO2 to the aquatic plants in your aquarium. Plants need CO2 to perform photosynthesis, a process by which they use light to convert carbon dioxide and water into the glucose they need for growth.

The use of a CO2 tank ensures your aquarium plants receive a consistent amount of CO2, contributing to vibrant, healthy growth. Moreover, by enhancing plant health and growth, a steady CO2 supply helps keep algae in check, as healthier plants compete with algae for resources.

CO2 Tank Certification

Before getting a CO2 tank, it's important to know about CO2 tank certification. In the United States, Department of Transportation (DOT) regulations require CO2 tanks to be tested and certified every five years. This hydrostatic test examines the tank's structural integrity to ensure it can safely hold pressurized CO2.

CO2 tanks should have a certification stamp indicating the date of the last inspection. It's essential to check this date when purchasing or refilling a tank. Using a tank that is past its certification date can pose safety risks.

co2 cylinder

How to Fill a CO2 Tank

Next, let's explore how to fill a CO2 tank. It's important to note that you should never attempt to fill a CO2 tank on your own unless you're trained to do so. Improper handling can lead to dangerous situations due to the high pressure inside the tank.

co2 cylinders

In most cases, you'll need to take your tank to a certified refill station. These could be local welding supply stores, fire extinguisher service companies, or specialized aquarium shops. They possess the necessary equipment and expertise to safely refill your CO2 tank.

Investing in a CO2 Tank

Investing in a tank of CO2 can significantly boost the health and vitality of your aquarium. With consistent and controlled CO2 supply, your plants will thrive, creating a more vibrant, natural-looking aquascape.

Using a CO2 tank responsibly involves regular monitoring of CO2 levels in your aquarium and adjusting as necessary. Tools like a CO2 drop checker can help with this, providing a visual indication of CO2 levels.

What thread should I choose for my CO2 regulator?

In the United States, CO2 tanks often come with a CGA320 valve, the standard for CO2 in the country. However, the regulator, which is the device responsible for controlling the rate of CO2 flowing out of the tank, may have a different connection type depending on the brand and model. It's crucial to ensure the regulator you're using is compatible with the CGA320 valve on your CO2 tank to ensure a secure, leak-free connection.

There can be instances when your CO2 regulator and cylinder valve don't match. This situation is common when you're using a specific CO2 cylinder type, such as Sodastream or Paintball bottles.

sodastream cylinder

Installing an adapter is generally a straightforward process, but it's essential to ensure a tight fit to prevent any CO2 leakage, for example by installing a special washer. These adapters come in various sizes and shapes, each designed to convert one type of connection to another. It's advisable to seek assistance from an expert or a reputable supplier to find the right adapter for your setup. They can guide you on the type of adapter you need and the correct way to install it, ensuring your CO2 system functions optimally and safely. Remember, managing a CO2 system requires attention to detail and safety considerations, and making sure your equipment connects correctly is an integral part of this process.


In conclusion, a CO2 tank is a valuable asset for any aquascaper. It offers a means to regulate the essential CO2 levels in your aquarium, promoting healthier plant growth and a more balanced aquatic environment. Whether you're a beginner or an experienced hobbyist, understanding the role and proper handling of a CO2 tank can go a long way in enhancing your aquascaping experience.