Aquarium CO2 System - Which one should I choose?

So you have decided to take your aquascaping to the next level and set up your first pressurized CO2 system? Choosing a CO2 system for aquarium use can often be an overwhelming experience, and sadly many people find this process too much, so they decide to leave it. We want to help you get the best system for your needs with as little stress as possible. In this article, read everything you need to know about choosing the most suitable kit.

Aquarium CO2 System - Which one should I choose?

Why is carbon dioxide so beneficial for planted tanks?

Why is co2 so crucial for aquatic plants? Carbon dioxide gas is an important element for aquarium plant growth. It is needed to produce the energy required for metabolic processes that help maintain healthy, vibrant plants. Photosynthesis will be limited without aquarium CO2 supplements, and growth will slow down or stop entirely. By having a pressurized CO2 system connected to your tank, you can supply your plants with the optimal amount of CO2 needed for growth. The correct carbon dioxide levels in your tank can also help maintain a healthy pH balance, which is essential for the health of both plants and fish. You can enjoy the lush greenery that adds life to your aquarium with the right system.

What do I need to build a fully automatic CO2 system aquarium setup?

Below is a list of the necessary items to create a reliable and fully automated CO2 system for your planted aquarium.

  • Two-stage regulator - This device adjusts the CO2 entering your aquarium. A two-stage regulator is designed in such a way that it can prevent an 'end-of-tank dump' when your CO2 cylinder becomes empty. Regulators also have a pressure gauge to indicate the working pressure or PSI. A quality regulator will have a secondary pressure gauge to show the level of CO2 present in the cylinder. Check the pressure gauge regularly to ensure your pressurized carbon dioxide system is running as it should.


  • Bubble counter - This item allows you to measure the amount of CO2 that enters your aquarium accurately. An adjustable bubble counter controls a bubble counter. By slight adjustments, you can increase the amounts of bubbles visible in the bubble counter to provide a higher CO2 flow rate. Additionally, adjusting the needle valve in the other direction can reduce the CO2 flow rate if needed. Only make slight adjustments and wait to see the effects before further changes.


  • CO2 diffuser - This item helps to break down the CO2 into smaller bubbles, increasing their surface area and allowing them to be absorbed by the aquarium water better. Many different types of CO2 diffusers are available on the market, but the most popular ones have ceramic membranes. By properly installing and maintaining your diffuser, you can ensure that the CO2 is efficiently distributed in your aquarium and that it is running as it should.


  • CO2-resistant tubing - A common mistake when it comes to the tubing is not to use a CO2-resistant material. Regular tubing will lead to breakage and leakage, which can be very dangerous for the aquarium environment. It is crucial to choose tubing specifically designed to withstand high pressure and temperatures associated with CO2 gas. This will ensure you get the most out of your CO2 system and your aquarium remains healthy and safe.


  • Check valve - A check valve is essential for any CO2 system as they help to prevent backflow into the pressurized tank, resulting in a more efficient distribution of CO2 into the aquarium. Our bubble counter has a built-in check valve; however, installing a check valve between the regulator and diffuser can prevent water from entering and damaging the regulator.


  • Drop Checker - To maintain the correct balance of CO2, a drop checker is necessary. This device helps to measure the levels of CO2 in your aquarium and, when combined with pH testing, will help you adjust levels as needed, ensuring your fish and plants get the right amount of carbon dioxide.


  • Socket timer/smart plug - This device helps you automatically turn your aquarium light, regulator, and other appliances on and off. With it, you can easily set up a daily schedule for your aquarium lighting and CO2 gas flow, allowing you to keep plants healthy without manually adjusting each day.

What size CO2 kit do I need CO2 for my planted aquarium?

Choosing an appropriately sized CO2 kit is important for the health of your aquarium. The size of the system will depend on the number and type of plants in your tank, as well as its volume. Generally, a larger tank requires more CO2 than a smaller one. You should also consider other factors, such as how much light you provide and whether you are using a filter. It is also advisable to seek advice from an experienced aquarist before purchasing a CO2 system for your aquarium.

Both our regulators are capable of running on larger and smaller aquariums. Additionally, with the help of various adaptors, you can use almost any sized CO2 cylinder as a source of CO2. The most important decision regarding size is your method of diffusion. Installing a suitable-sized diffuser for your aquarium will ensure that the right amount of CO2 enters and leaves the tank, thus maximizing its effectiveness.

Before purchasing one of our complete co2 systems for aquariums, make sure you consider all the factors that may influence your decision. We offer a wide selection of regulators, diffusers, and CO2 accessories so you can find the perfect combination that fits both your budget and aquarium needs. With quality components, our complete co2 systems are designed to last while offering maximum performance. Be sure to read through our product pages.

Our best-rated CO2Art Complete Kit with Pro-Elite Regulator and Inline CO2 diffuser- find more in our shop!


I have an open-top aquarium. Is this compatible with a Freshwater CO2 system?

Running a CO2 system on an open-top aquarium is common, and many of the most beautiful displays are open-top systems. There are a few things to consider if you have an open-top system. First, the CO2 gas will likely escape faster than in a closed-top aquarium. This means that you may need to run your CO2 system longer each day and increase the dosage of CO2. However, when lights are off, the CO2 levels will deplete faster, and this will help aquatic plants to produce oxygen much quicker.

Another thing to consider when using a CO2 system on an open-top aquarium is the equipment. Using an in-tank diffuser will require tubing to travel from the diffuser itself all the way to the regulator. This can be difficult to route and manage, not to mention loose cables hanging over the side of your beautiful planted tank will ruin the aesthetics you worked hard to create. We offer three sizes of U-bends designed to minimise this issue. Made from a stylish and sleek stainless steel material, they do a great job of keeping things in check.

I have nano tanks. What is the best aquarium CO2 system to use?

As mentioned above, both our regulator options apply to any aquarium size. The big decision when your planted tank is on the smaller side comes down to your diffuser type. We suggest using a ceramic diffuser for nano tanks as it will produce smaller bubbles and disperse the CO2 more evenly, resulting in maximum effect. There are two models of in-tank diffusers. Both have a ceramic membrane that utilizes our nano-mist technology to produce tiny bubbles that slowly dissolve into the water column.
If an in-tank diffuser is not what you fancy, you could install an inline diffuser in your canister filter. Typically considered if you have a larger tank, the inline diffuser can also be very effective on smaller tanks. The in-line diffuser attaches to the tubing on your external canister filter outlet, and as CO2 is added, it travels through a ceramic membrane and into the fast-flowing water. Many of the tiny bubbles diffuse before they even enter the aquarium.
Before selecting an in-line diffuser, always confirm the tubing width on your canister filter outlet.

Pre-purchase checklist.

Before purchasing your first (or next) pressurized CO2 system, here are some simple questions to ask yourself. The answers to these questions should help you identify the best collection of products for your needs.

  1. How many tanks? - If you are planning to inject CO2 into more than one aquarium, you may want to consider our Pro Elite series regulator. It can manage many aquariums from a single source of CO2, reducing your running costs and saving space.

  2. Which source of CO2 will I be using? - You will need to select the correct fitting for your regulator, depending on the source of CO2 you plan to use. A regulator from CO2Art has the standard thread type designed to connect with a fire extinguisher. However, it is possible to connect to almost any type of CO2 cylinder by using the correct adaptor. Always ensure you have a regular source of CO2 available to avoid running out of CO2 and allowing algae to take over.

  3. What type of diffuser? - Do you want an in-tank or in-line diffuser? Understanding the size of your aquarium and the fittings of your external canister tubing will avoid purchasing the wrong diffuser size.

Paying attention to these three points in advance will make purchasing your pressurized CO2 kit much more straightforward.

Aquarium CO2 System - Which one should I choose?

Are Carbon dioxide gas and easy CO2 for aquarium plants the same thing?

The short answer to this question is no. They are not the same. Carbon dioxide gas is a chemical compound with three oxygen atoms bonded to one carbon atom. At the same time, easy CO2 for aquarium plants is a liquid form of carbon dioxide specifically formulated for fish tanks. This includes other ingredients, such as trace elements and calcium which can help promote healthy plant growth in an aquarium setting. Both aid the growth of aquarium plants but in very different ways. Liquid "CO2" kills algae and reduces the competition for nutrients within the aquarium. By doing this, many plants can access more CO2 gas and fertilizers, making them healthier. Dissolved CO2 gas forms an integral part of plant photosynthesis and is converted into energy for the healthy development of aquatic plants.


It's important to remember that too much carbon dioxide can be dangerous for fish and plants by causing a sudden drop in pH levels. As a result, it's crucial to monitor the amount used and check for any signs of distress from your fish or plants. You can keep your aquarium healthy with careful monitoring and regular water changes!

Any questions? Our Customer Service is always ready to answer them! Contact us directly via!