7 Best CO2 Diffusers – Reviews & Buying Guide

Best CO2 Diffuser

Plants require CO2 to grow and release oxygen back into the air. In planted tanks, these plants release oxygen back into the water and in the process, they make their environment more and more unconducive for them to live in.

For this reason, it is necessary to increase the CO2 content in the water. Bubbling the gas through the water won’t be enough to increase its level because of the reduced surface area for absorption.

This is where a CO2 diffuser comes in. Basically, diffusers operate like air stones by creating smaller bubbles of the pressurized CO2 and this increases the surface area for absorption of the gas into the water.

That said, there are different types of CO2 diffusers that come in different shapes and sizes, with most of them being made of glass. This article looks at the best CO2 diffusers in the market so as to make it easier for you to select the best one for your tank.

7 Best CO2 Diffusers – Reviews

Product Name

Image

​Features/Benefits

Rating

Current Price

1. Pm0606 Micro Oxygen and CO2 Bubble Diffuser


Pm0606 Micro Oxygen and CO2 Bubble Diffuser

Plant and fish compatible CO2 diffuser with an air flow control valve and a ceramic disc for bubble creation

4.1

2. Jardli Pollen Glass CO2 Diffuser with U-Shape Connecting Tube

Jardli Pollen Glass CO2 Diffuser with U-Shape Connecting Tube

A glass-made CO2 diffuser that is available in two sizes, each utilizing a ceramic disc for CO2 atomization

4.2

3. Jardli Glass CO2 Diffuser

Jardli Glass CO2 Diffuser

Aesthetically good-looking glass CO2 diffuser with a U hanger design and a small ceramic disc

3.9

4. Fibst CO2 Diffuser for Aquarium

Fibst CO2 Diffuser for Aquarium

Stainless-steel-made CO2 diffuser with a U hanger and a ceramic disc for creating gas bubbles

3.9

5. Yagote Glass CO2 Diffuser

Yagote Glass CO2 Diffuser

Affordable CO2 diffuser with a beautiful spiral design made out of fine see-through glass

3.4

6. Jardli Music Glass CO2 Diffuser

Jardli Music Glass CO2 Diffuser

Glass-made CO2 diffuser with a large 2-inch ceramic disc that makes it suitable for over 75-gallon tanks

3.7

7. Atman Enhanced Dissolution CO2 Diffuser

Atman Enhanced Dissolution CO2 Diffuser

Very efficient CO2 diffuser with a ceramic cylinder in an enclosed system for 100% dissolution in water

5.0

1. Pm0606 Micro Oxygen and CO2 Bubble Diffuser

Our pick for the best CO2 diffuser

Editor's Rating: (4.1 / 5)

Pm0606 Micro Oxygen and CO2 Bubble Diffuser

Pm0606’s product is one of the best CO2 diffusers for aquariums because, apart from being supportive of plant growth, it is compatible with shrimps, guppy, tetra and betta fish among many others.   

The diffuser is designed to create micro-fine bubbles, which increase surface area for contact with the water, leading to a very large absorption of CO2 gas. This is made possible by the use of a ceramic disc, which helps in releasing the gas in very tiny amounts, forming the fine bubbles.

An air control valve is included in the package and this helps in regulating the amount of CO2 that goes into the tank as well as the size of the bubbles being produced.

In terms of size, this product is available in a small, big, large and stick size, with the stick being very effective at creating a large number of bubbles on a wide, distributed surface for the highest rate of absorption.

The disadvantage with this diffuser is that it does not come with the required tubing and it requires regular cleaning, especially on the white ceramic.

However, this is a very simple task because of the small size and smooth surfaces of both the glass body and ceramic, which are easy to clean.

Pros:

  • Good for plants and fish
  • Creates micro-fine bubbles for maximum CO2 absorption
  • Air control valve for regulating CO2 release
  • Available in 3 sizes plus a stick model
  • Easy to clean

Cons:

  • Requires regular cleaning
  • Does not come with the required tubing

2. Jardli Pollen Glass CO2 Diffuser with U-Shape Connecting Tube

Still one of the best CO2 diffusers

Editor's Rating: (4.2 / 5)

Jardli Pollen Glass CO2 Diffuser with U-Shape Connecting Tube

Jardli’s CO2 diffuser also features a ceramic disc that provides efficient CO2 atomization for maximum absorption into the water.

For more effectiveness, this product is available in wide 1.5- and 2-inch diameter options, with the 1.5-inch option being suitable for 20 – 50-gallon tanks and the 2-inch option being suitable for 50 – 75-gallon aquariums.

These are wide enough for distributing the CO2 over a larger surface area for better absorption and this makes them one of the best CO2 diffusers for planted tanks because they saturate the water as much as possible.

The ceramic disc and its glass housing are connected to the outside using a glass U-tube, which means that the unit has a very fragile body. However, glass is very easy to clean and thus, it is very easy to maintain.

On the downside, this diffuser does not have an air flow control feature. Instead, it has a very simple design that does not require adjustments every now and then.

Pros:

  • Ceramic disc for efficient atomization
  • Available in two sizes
  • Suitable for 20 – 75-gallon tanks
  • Easy to clean glass body

Cons:

  • No CO2 flow control valve
  • Glass construction makes it very fragile

3. Jardli Glass CO2 Diffuser

Aesthetics combined with performance

Editor's Rating: (3.9 / 5)

Jardli Glass CO2 Diffuser

This product is also a Jardli CO2 diffuser like the one above and thus, some features are similar between the two.

For instance, both are made using glass and have a U-shape design. This one, however, has an extended glass tube that forms a U at the top for hanging it. Such a design enhances the aesthetic beauty of the aquarium because of the glass hanger.

Although this unit does not come with the required tubing for installation, the U hanger minimizes the length of tubing that you have to buy since part of the glass hangs outside the aquarium, closer to the gas tank.

A ceramic disc is featured for CO2 atomization, but it is quite small as compared to the one in the pollen diffuser above. It measures only 0.8 inch in diameter and this makes it ideal for tanks that are less than 20 gallons in capacity (Nano tanks).

The small size, however, means that it is much easier to clean and requires less bleach water to do the job.

Pros:

  • Aesthetically beautiful U glass hanger
  • Requires less tubing
  • Ceramic disc for creating CO2 bubbles
  • Easy to clean

Cons:

  • Does not come with the required tubing
  • Very small ceramic disc

4. Fibst CO2 Diffuser for Aquarium

Most aesthetically beautiful CO2 diffuser

Editor's Rating: (3.9 / 5)

Fibst CO2 Diffuser for Aquarium

Fibst’s CO2 diffuser is quite unique because it is made of 304 stainless steel and this not only makes it strong and durable but also gives it a mirror-like finish, which looks very elegant underwater.

To add onto this, it has a similar U-shaped hanger like Jardli’s unit above, making it look more of a decoration than a CO2 diffuser.

The only problem though is that it has a small ceramic diffuser, measuring only 30 mm in diameter (slightly above 1 inch). A 20 mm option is also available and both sizes are ideal for use in Nano tanks.

Regardless of the size, the ceramic in each unit is safely secured inside a cup, which must be opened if you want to clean the disc. This ensures that no CO2 escapes without passing through the ceramic while also making it easy to clean since the disc is easily removable.

Pros:

  • Strong and durable stainless-steel construction
  • U-shaped hanger and a mirror-like finish give it a good look
  • Easy to maintain
  • Ceramic disc for CO2 diffusion
  • Available in 2 sizes

Cons:

  • Small CO2 diffuser surface area
  • No flow control valve

5. Yagote Glass CO2 Diffuser

Best CO2 diffuser for the money

Editor's Rating: (3.4 / 5)

Yagote Glass CO2 Diffuser

Yagote’s CO2 diffuser is the most affordable product on this list but this does not mean that it is a low-quality product.

The unit actually has a very intricate design consisting of a spiral glass in a glass cup, which is a very beautiful design to have on your aquarium. Additionally, this fine see-through glass blends very well with the water, creating a sense of harmony and unity with the tank.

A ceramic disc is installed above the cup for diffusing the gas. It contains atomic pores on its surface that release the gas in very small portions, leading to the very fine bubbles that exit on the other side.

However, this disc is very small in size, measuring only 3/4 inch in diameter, making it suitable for 15 – 50-gallon planted tanks.

If you have a bigger aquarium, there is a 1.6-inch option that is suitable for 30 – 50-gallon tanks and a 2-inch option that is suitable for 50 – 75-gallon aquariums. With these options, you will certainly get a perfect match for your tank.

In terms of installation, a suction cup is included for fixing the diffuser on the glass wall firmly and that’s it. All you have to do is attach tubing to connect it to the pressurized CO2 canister.

Pros:

  • Affordable
  • Beautiful spiral design
  • Ceramic disc diffuser
  • Available in 3 sizes
  • Easy to install

Cons:

  • Fragile glass construction.
  • Small ceramic disc size

6. Jardli Music Glass CO2 Diffuser

The best CO2 diffuser for big tanks

Editor's Rating: (3.7 / 5)

Jardli Music Glass CO2 Diffuser

Jardli’s music glass CO2 diffuser is quite expensive but this is because it has a 2-inch diameter ceramic disc that is designed for larger tanks with capacities of 75 gallons and above.

In terms of design, the unit closely resembles a small coffee cup with a tube rising high above it. It does not come with the required rubber tubing but its glass tube is standard sized to connect with 4/6 mm tubing. On the bright side, it comes with 2 suction cups for easy installation.

An important thing that you need to note is that the whole diffuser should be soaked in water for at least 30 minutes before use and the glass tube should be inserted in water before connecting it to the rubber tubing. This will prevent any damages to the glassware.

Pros:

  • 2-inch diameter disc for use in large tanks
  • Ceramic disc for efficient atomization of CO2 gas
  • Comes with 2 suction cups for easy installation

Cons:

  • Does not come with the required tubing
  • Expensive

7. Atman Enhanced Dissolution CO2 Diffuser

Most efficient CO2 diffuser

Editor's Rating: (5 / 5)

Atman Enhanced Dissolution CO2 Diffuser

Atman’s unit is the top-rated CO2 diffuser in this list and this is because it achieves a 100% dissolution in water, making it a very good accessory for planted tanks.

To achieve this, the diffuser is designed quite differently as compared to the other units above. Instead of being placed inside the tank, it is connected to the outlet from an external filter, from which it carbonizes the water with no CO2 loss.

Read More: 10 Best Aquarium Filters

A ceramic cylinder is used to create the bubbles, with the water passing inside while CO2 is forced into the water from outside the cylinder. This cylinder is enclosed inside the diffuser’s main body and this ensures that there is no gas lost, which is very efficient.

The only problem with this system is that the ceramic requires to be replaced every 6 – 8 months, which is an expensive option as compared the cleaning required in the other models.

Other features include a bubble counter, an integrity check valve and 2 suction cups for easy installation on the tank wall.

Pros:

  • Achieves a 100% dissolution in water.
  • Ceramic cylinder diffuser
  • Features a bubble counter
  • Comes with 2 suction cups for easy installation

Cons:

  • Requires a functioning filter in order to work
  • Ceramic requires replacement instead of cleaning

How to Buy the Best CO2 Diffuser

How to Buy the Best CO2 Diffuser

#1. Compatibility

Before buying a CO2 diffuser, you should check its compatibility in terms of the tank size that it can handle.

This is usually determined by the size of the ceramic disc. The smaller the disc, the smaller the surface area for releasing CO2 bubbles and thus, the smaller the tank that it can handle.

Most units with ceramic discs that are 2 inches or larger in diameter are ideal for large tanks of over 70 gallons, but this is just a rough guide. Ensure that you always check a diffuser’s tank capacity rating before buying so that you do not over or under saturate your tank with CO2.

#2. Material

CO2 diffusers are usually made from either glass or stainless steel. While glass blends very well with the tank water, it is very fragile and thus, such CO2 diffusers must be treated with care.

Stainless steel, on the other hand, makes the diffusers have a mirror-like appearance underwater, which is still a good finish. The biggest advantage with this construction though is that it is very strong, which means it does break easily and does not require delicate handling.

If you are a clumsy person, you better go for the stainless-steel unit. However, if you can handle glass carefully, a glass CO2 diffuser is the best one for you.

#3. Ease of use

A diffuser’s ease of use is mostly considered in terms of how easy it is to clean.

Diffusers with ceramic discs are very easy to clean because you only need to use a bleaching agent to remove the discoloration, then rinse it thoroughly.

However, some products require the ceramic to be replaced after a certain amount of time and this makes it easier to maintain since a replacement means that no cleaning is required.

#4. Accessories

Accessories are also a big thing to consider because they save you the cost that you would otherwise incur in buying the items.

In terms of CO2 diffusers, the accessories to look for in the package include an air flow control valve, which regulates the amount of CO2 that goes into the diffuser cup and ceramic disc. With this, you get to have more control over the rate of release of the gas into the tank.

Suction cups are also an important thing to consider because they are used in the installation process by helping you stick the unit to the aquarium wall.

Although most diffusers do not come with their required rubber tubing, this is still a very valuable addition and thus, if you get a diffuser that comes with its tubing and at a good price, the better.

Best Place to Put the CO2 Diffuser 

There are a few things to consider before deciding on where to place the CO2 diffuser in the tank. First of all, if it is an inline unit such as Atman’s diffuser in the review above, there’s no debate about it. It should be placed on the return lines from an external filter.

For the in-tank unit though, the best place to install it is close to the bottom of the tank. At this depth, bubbles will take a longer time to reach the surface and thus, more CO2 will be absorbed.

To make the bubbles spend more time in the water, the position that you select should be under the return lines of the filter. This way, the water will push the bubbles back into the water for more CO2 absorption.

An important thing to note is that you should not place the unit under the substrate or among the plants. The idea here is to let the bubbles flow freely without any interference.

If they encounter the substrate or plant leaves, they might combine to form larger bubbles, which reduces the surface area for the gas to dissolve and thus, a lot of CO2 will go to waste.

Conclusion

Whether you have a freshwater or a saltwater planted tank, you will most likely need additional CO2 to help the plants grow stronger and healthier.

The products described above are the best CO2 diffusers that can help you with this and therefore, it is important to go through this article so that you can be able to pick the most suitable one for your planted aquarium.

Read More: 7 Best UV Sterilizer Aquariums

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