6 Best Aquarium CO2 Diffusers | 2022 Reviews

If you have an aquarium at home or inside your working establishment, you may notice some aquatic plants looking pale or fishes suddenly floating dead. One of the main reasons for this is because you do not use a CO2 diffuser for your aquarium.

A CO2 diffuser, in a nutshell, diffuses a certain amount of carbon dioxide inside the aquarium to support the aquatic plants with their needs for photosynthesis. Plants need this for their growth and to give off the nutrients required by the fish to eat.

Selecting a CO2 Diffuser might be a challenge for you. Thankfully, you’ve found the ultimate guide to buying the best CO2 diffuser. Here are some of the best CO2 diffusers with their Pros and Cons. You will also know more about what a CO2 diffuser is, how it functions, and the many benefits you can get from it.

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Best Aquarium CO2 Diffuser Reviews

Fibst CO2 Diffuser

Made with stainless-steel and ceramic dome to cover it, Fibst CO2 diffuser stands the test of time underwater.

You have the option to select from three different sizes—these range from around 10 to 30 gallons of water. You will see the intake tubes at the bottom of the dome curving up in a J-bend that extends to a full 13 inches, then curves the other way to form the U-bend over the side of the aquarium.

This diffuser does not include a bubble counter and check valve. The fixed length of the intake tube limits the height of the diffuser inside the aquarium.


  • It has high durability because of its stainless-steel design
  • Cleaning and disassembly is easy
  • Parts can be easily replaced
  • Comes with a warranty of 6 months for the dome and 24 months for the other parts


  • It does not have a bubble counter and check valve
  • It cannot be used for tanks above 30 gallons

Aquario Neo CO2 Diffuser

In this list, the Aquario Neo CO2 Diffuser is the only one that can work in a DIY system. The outer portion of the diffuser uses clear acrylic, making it more durable than glass. It has undergone a drop test, and it passed with flying colors.

Regarding its intake, it forms a J-bend that passes underneath but then forms a cylinder. It has a long intake tube , and uses a suction cup to attach itself to the aquarium.

You can adjust its height because its U-bend is not fixed. But the downside here is that it doesn’t come with a bubble counter and check valve. You cannot detach the ceramic disk, making it hard to clean. It works best with small and medium-sized tanks.


  • Because of its acrylic design, it is more durable than other diffusers
  • It can diffuse CO2 even under low water pressure
  • You can adjust the height of the diffuser
  • Generates smaller bubbles underwater


  • It does not contain a bubble counter and check valve
  • Cleaning would be a challenge because you can’t remove the ceramic disk

NilocG Aquatics | Intense Atomic Inline Co2 Atomizer Diffuser

Since NilocG Aquatics Co2 Atomizer Diffuser works as an atomizer, it gives off a high rate of CO2 diffusion like none in this list. CO2 being diffused dissolves 100% underwater because of the fine bubbles it produces. The CO2 reactor makes sure that the bubbles released would have an average bubble size less than 0.1 mm in diameter.

This diffuser is simple to install with the option of mounting it below or directly to your aquarium. Contains and inline design for use with canister filters. Made from stainless steel and ceramic ensure the quality and durability of this diffuser.

It is important to note that this diffuser requires a minimum pressure of 30 PSI or it won’t work efficiently.


  • Made from stainless steel and ceramic making it durable
  • Diffuses tiny bubbles
  • It is user-friendly and can be placed in desired spots in the tank
  • It has a 100% dissolution rate underwater


  • Does not include water-resistant tubing
  • Cost more

Hygger Aquarium Air Stone

The Hygger Aquarium Air Stone features a round oxygen stone surrounded by a ceramic disc. It acts like an atomizer that diffuses bubbles of a small size. You can adjust the size of the bubble it releases depending on your preference.

Installation is a breeze with three easy steps. First, attach the tube to your diffuser’s pin. Then drop it underwater. Finally, turn on the pump.

The nano-stone releases more bubbles into your tank than regular bubble stone. This means more dissolved oxygen for your tanks inhabitants.

One thing to consider is your tank size. This diffuser fits best with small to medium sized tanks.


  • It looks cool underwater as it blends well with the rocks underneath it
  • It diffuses tiny bubbles that increase the efficiency of CO2 diffusing inside the aquarium
  • Easy installation
  • Affordable


  • A hose and air pump are not included
  • It can only be used with small and medium-sized tanks

BASE WAVE Mini Transparent CO2 Diffuser

The BASE WAVE Mini Transparent CO2 Diffuser is great for smaller tanks. It is made from stainless steel and suitable for glass less than 0.7 inches.

This diffuser comes with six feet of standard CO2 tubing. It makes tiny bubbles and works under low water pressure.


  • It uses a stainless-steel design combined with a ceramic disk on its sides
  • It releases bubbles of small sizes, making it a good CO2 diffuser
  • It works even under low water pressure
  • Affordable


  • There is no water-resistant tubing included in the kit
  • Leaks around base a bit

JARDLI Glass Lily Pipe Outflow for Aquarium Planted Tank

If you’re looking for an aesthetically pleasing CO2 diffuser that gets the job done, then JARDLI Glass Lily Pipe Outflow for Aquarium Planted Tank might be the choice for you. The clear clamps and suction cups compliment the tank glass very well. The cup angles linear after placement for a more pleasant look.

It diffuses CO2 in an ample amount, and you can easily attach it to your tank.


  • Gives an “invisible look” in your tank
  • Made from thick glass
  • Installation is easy
  • It is easy to clean


  • The diffuser is made from glass making it more fragile
  • It does not include the U-bend and check valve, which could mean spending more later on

What is a CO2 Diffuser and How Does it Work?

A CO2 diffuser allows CO2 to spread throughout the aquarium effectively. Aquatic plants inside your aquarium require CO2 for growth and respiration purposes. Without it, these plants cannot undergo the process of photosynthesis, and they will wither.

Unlike in the wilderness, plants on land and sea can acquire their source of CO2 from degrading plants and other outside sources. But, when the plants are inside an aquarium, they have a limited supply of CO2. Therefore, the need of having a CO2 diffuser is essential. So how does it work?

A pressurized bottle filled with CO2 connects to a regulator. This regulates the amount of CO2 that enters the aquarium. Then from the regulator, it connects to a bubble counter. This bubble counter shows the amount of CO2 you released from the bottle.

Finally, the CO2 passes through a CO2 tubing connected to the bubble counter. This gives off CO2 supply to the aquarium, thus completing the process.

Benefits of a CO2 Diffuser

Owning a CO2 diffuser has a lot of benefits. Many people fail to see the benefits of using a CO2 diffuser because of the additional cost. They would be surprised if they know about these benefits and how it could help their aquarium look better.

Everyone knows that fishes and plants need each other to live. The plants need carbon dioxide to thrive, and many fishes feed on plants to survive. The amount of CO2 can affect the growth of plants. If the plants couldn’t have the right amount of CO2, they would have lack lustered leaves and stems.

Their growth would surely slow down. Thus, aeration of the environment would be affected, and the nutrients it provides the fishes would be scarce. This situation can be avoided with the installation of a CO2 diffuser.

It’s interesting to learn that CO2 also plays an important part in the life of the fishes. Fishes exude carbon dioxide during respiration. When there is too much CO2 in the water, it increases its pH balance, making it a dangerous habitat for the fishes to live in. This will make the fishes look sickly, or even worse; dead fishes would appear.

Too much CO2 also contributes to algae growth. Algae threaten the life of fishes by making their environment dirty. Algae lead to excess ammonia, which is dangerous for fish. With a CO2 diffuser, the amount of CO2 entering and leaving the aquarium will be regulated to the right amount; thus, eliminating this problem.

Types of CO2 Diffusers

CO2 Reactors

This type of diffuser does not directly release CO2 gas in the aquarium. A separate reactor mixes the CO2 with the aquarium water. This process aims to properly mix carbon dioxide with the aquarium water, then releasing the final CO2 water inside the aquarium.

In-Line CO2 Diffuser

Known as the most conventional type of diffuser in the market, an in-line CO2 diffuser could be very effective when used correctly. Take note of the stream of mist being produced by this diffuser. To achieve this fine stream of mist, one must consider the following pointers:
proper placement of the diffuser in the tank
keeping the filters clean at all times
checking clogs on tubes

Ceramic CO2 Diffuser

A ceramic CO2 diffuser usually features a round construction that connects to a plastic body. It looks like a donut in some cases, and it functions as an in-line CO2 diffuser. The difference between the two is on how to place the diffuser. It acts like a suction cup and sticks on the side of the aquarium.

Airstone Diffuser

An airstone diffuser looks like a disc with a pin on top that diffuses air inside the aquarium. Air pumps produce carbon dioxide to the airstone diffuser, creating an abundant cascade of tiny bubbles. It eliminates the movement of water through the filter, making it more effective.

Ladder CO2 Diffuser

A ladder diffuser works similarly to an In-Line CO2 Diffuser with new features and advantages. Unlike the in-line diffusers, it requires less cleaning because of its structure, and it performs more efficiently due to the way it produces air bubbles. Although it looks bigger inside the aquarium, it still has many benefits over the in-line diffuser.

How to Choose the Best CO2 Diffuser

Tank size and Flow

Your tank’s size matters a lot when choosing a CO2 diffuser. CO2 diffusers have different tank size specifications that could affect airflow if the diffuser is not right for your tank. There will be instances that if you buy a smaller diffuser for bigger tank size, it will not give off the right amount of CO2 required for your plants and fishes.

What does the kit include?

Upon buying a new CO2 diffuser kit, the following equipment would be included: U-bends, bubble counters, check valves, a regulator, and CO2 tubes.

Frequently Asked Questions about CO2 Diffusers

u003cstrongu003eDo you need a CO2 Diffuser for your tank?u003c/strongu003e

It is a must to have a CO2 diffuser for your tank. It gives your tank, plants, and fishes many benefits, like providing enough carbon dioxide for photosynthesis. Also, it regulates the carbon dioxide inside the aquarium, making the water inside the tank have a balanced pH level.

u003cstrongu003eHow do I install a CO2 diffuser?u003c/strongu003e

You will see many CO2 diffusers on the market. Installation of these diffusers varies per model. But even in these cases, there are basic steps to remember to install a CO2 diffuser properly.u003cbru003eu003cbru003eUpon placing the CO2 tank in its place, you need to look at your check valve. This helps with the regulation of water and CO2. The next device to be checked should be your bubble counter. This shows you how fast the CO2 gas travels inside the aquarium. Then properly install your U-bend since this tube hardens over time and can affect the airflow if not correctly installed.u003cbru003eu003cbru003eLastly, the diffuser is placed at the end of the line. It should be placed near the bottom of your aquarium. You would want the bubbles to be underwater and not above it.

u003cstrongu003eWhere should I place my CO2 diffuser?u003c/strongu003e

The CO2 diffuser should be placed towards the bottom of your tank. This is for the bubbles to spend much time underwater, and CO2 diffusion would be maximized.

u003cstrongu003eHow long should I run CO2 in my aquarium?u003c/strongu003e

The best time to run your CO2 would be an hour after your aquarium’s lighting turns on until the time it turns off. This would help in the photosynthesis process of the aquatic plants inside. This would depend on how long do you set your lighting inside the aquarium.

u003cstrongu003eShould I turn off CO2 at night?u003c/strongu003e

It is essential to turn off CO2 at night. Plants produce CO2 at night and don’t use the CO2 from the diffuser. Because of this the amount of CO2 inside the tank might increase, and the water’s pH level would be affected. This will be harmful to the fish inside the tank.

u003cstrongu003eWill adding CO2 reduce algae?u003c/strongu003e

Adding more CO2 increases the growth of algae. The purpose of your CO2 diffuser is to regulate the amount of CO2 inside your tank. If the amount of CO2 exceeds a certain number, then algae growth would be inevitable. CO2 diffusers eliminate that problem by proper regulation.

Final Thoughts on the Best Aquarium CO2 Diffuser

You have quite a bit of research to do before you find the best CO2 diffuser. But it pays to spend extra time doing the hard work instead of choosing a diffuser using pure guesswork. Hopefully, this guide will point you in the right direction as you search for a CO2 diffuser that fits both your needs and budget.

Looking for more gear for your aquarium? Head over to our Aquarium Gear section to see more reviews.

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