A Guide to Best CO2 Diffuser

A Guide to Best CO2 Diffuser in 2020

People often consider a CO2 diffuser to be an unnecessary device. This is a completely false ideology – they are almost an essential part of a planted tank.

Aquatic plants occasionally feel a shortage of CO2 in the tank and can’t produce enough food for themselves. As a result, they tend to grow at a timid pace. In severe cases, they could even die!

So, CO2 for aquarium plays a vital role.

The best CO2 diffuser will help you make a balance between CO2 and O2 in the tank.

You can overlook them if you don’t have live plants in the tank.

Generally, a CO2 diffuser is a simple device that follows a simple design principle. It takes CO2 from a tank and converts the gas into small bubbles that diffuse with the tank water.

So, I will skip the buying guide in this article. However, I have given answers to all the common questions regarding the device.

Let’s start then!


​Tank Size



JARDLI Pollen Glass CO2 Diffuser with Bubble Counter

​10-20 gallons

PM0606 Micro CO2 Bubble Diffuser

​40 gallons

Fluval 20g

​​10 gallons

JARDLI Pollen Glass CO2 Diffuser with U-Shape Connecting Tube

​20-50 gallons

JARDLI Glass Inline CO2 Atomizer Diffuser System

​10 – 20 gallons

Sera Flore Active CO2 Reactor 500

​66-160 gallons

Fibst CO2 Diffuser for Aquarium

​90 gallons

Top 7 Best CO2 Diffuser That You Can Get In 2020

​1. JARDLI Pollen Glass CO2 Diffuser with Bubble Counter – The Best CO2 Diffuser

JARDLI Pollen Glass CO2 Diffuser with Bubble Counter

When it comes to making CO2 diffusers, JARDLI is the name that comes to my mind before any other. They are simply the market leader, and no other manufacturer is even close to them.

JARDLI is the “Apple” of the CO2 diffuser industry!

So, what is so special about the JARDLI Pollen Glass CO2 Diffuser with Bubble Counter?

The first thing is the looks. As you cannot hide the CO2 diffuser behind anything in the tank, the looks of the device become crucial.

The top-notch glass design is something to die for! And, when it comes to operation, the device works like a charm.

Don’t believe me?

Just check out the specs.

Notable Features

  • ​- Comes with built-in bubble counter
  • CO2 emits efficiently through the ceramic membrane that is permanently attached within
  • Suitable for smaller tanks, preferably under 20 gallons
  • The ceramic membrane has a diameter of 0.8” (2cm)
  • Fits with the commercial 4/6mm tubes
  • Pros

    • ​The bubble counter comes within the package
    • ​Aesthetically pleasing
    • ​Completely glass made
    • ​Small in size


    • ​Doesn’t have the U-bend or check valve
  • 2. PM0606 Micro CO2 Bubble Diffuser – The Value Champ

  • PM0606 Micro CO2 Bubble Diffuser

    If you are looking for something premium without worrying about the pricing, PM0606 Micro is the best thing that you can get.

    It seems that the manufacturers were so concerned about the finish quality of the product. Once you touch the CO2 diffuser, you will understand what I am talking about. 

    The ceramic disk has a perfect diameter of 1” that can produce microbubbles.

    Having a glass-made CO2 diffuser always leaves a risk of breaking. The good thing is that the device is made of strong materials will not likely to break.

    This is a perfect CO2 diffuser DIY product.

    Notable Features

  • ​- Made of high-grade sturdy materials
  • The ceramic disc ensures lossless 100% CO2 diffusion
  • Has easy-to-count bubbles shooting from clear acrylic cylinder
  • All the components are 100% washable
  • The ceramic disk has a 1” diameter
  • Pros

    • ​Superior build quality
    • ​100% diffusion rate
    • ​Washable components
    • ​Micro seized bubbles
    • ​Comes with bubble counter
    • ​Air control valve to control the CO2 emission


    • ​Doesn’t come with the tubes
  • 3. Fluval 20g-CO2 Diffuser – Best CO2 Diffuser for 10 Gallon Tank

  • Fluval Co2 Diffuser

    In the market of the aquatic pet industry, Fluval is a name that is certain to come at any point. This time, Fluval is presenting you with a small, sleek, yet powerful device.

    I am talking about the Fluval 20g CO2 Diffuser.

    Rather than using the fragile glass body, they have used clear acrylic diffuser that looks as clear as the glass but will be much more durable.

    The best part about the Fluval CO2 kit is that you can easily assemble or disassemble it for your convenience. Moreover, you can get all the replacement parts from local shops.

    Notable Features

  • ​- Made of clear acrylic materials
  • Suitable for planted nano tanks
  • Cheap and small; weighs only 20g
  • All parts can be disassembled
  • Pros

    • ​Simple and small in size
    • ​Perfect for small tanks
    • ​The acrylic body will not break easily
    • ​Easy to wash
    • ​Budget-friendly


    • ​Can’t handle large tanks
    • ​Doesn’t come with a bubble counter and check valve
  • 4. JARDLI Pollen Glass CO2 Diffuser with U-Shape Connecting Tube

  • JARDLI Pollen Glass CO2 Diffuser with U-Shape Connecting Tube

    As I have said, JARDLI is the market leader. They have a wide variety of products available for different types of users.

    This has to be one of the most beautiful models out there. The first thing you will notice about JARDLI Pollen Glass CO2 Diffuser is the U-Shape connecting tube.

    However, that is not the specialty of JARDLI CO2 diffuser. That would be the pollen sized tiny CO2 bubbles that it shoots from the large 1.5” ceramic disc.

    Having a large ceramic disc, you can use it in a large tank having 30 to 50 gallons of water. The two suction cups will make the installation process a piece of cake.

    Notable Features

  • ​- The CO2 atomization process is nearly perfect the shoots pollen sized bubbles
  • U-Shaped tube allows a block-less CO2 emission
  • Uses suction cups for easier installation
  • The Ceramic disc is permanently attached to the device
  • Ensures up to 98% CO2 diffusion
  • Made of high-quality glass
  • Suitable for large tanks
  • Pros

    • ​Spectacular looking device
    • ​Great diffusion rate
    • ​Comes with built-in bubble counter
    • ​Can generate very tiny bubbles


    • ​Irreplaceable discs
    • ​Glass-build is not very durable
  • 5. JARDLI Glass Inline CO2 Atomizer Diffuser System – The Premium Choice

  • JARDLI Glass Inline CO2 Atomizer Diffuser System

    Okay, I understand that I sound more like a salesman from JARDLI, but just look at this masterpiece!

    Rather than looking like an aquarium device, it looks more like art!

    The unique inline design allows the device to incorporate turbulent mixing that results in better dissolution. It creates a mist-like flow of CO2 that no other diffuser can offer.

    If you are already using a canister filter, JARDLI Glass Inline can become the perfect partner for it. The tubing holes are specially designed to match the universal canister filter tubing.  

    They have designed the CO2 diffuser in a way so that it can be “inline” with the cannister filter below it.

    The device material also disallows algae growth on the disc because of the design philosophy.

    Notable Features

  • ​- Uses turbulent mixing process so that CO2 saturation in the tank can increase
  • Creates a CO2 mist for better CO2 absorption for the plants in the tanks
  • Designed to work as a partner for the cannister filters
  • Fits perfectly with the cannister filter tubes of 5/8” diameter (16/22mm)
  • The special design doesn’t let algae growth on the ceramic membrane
  • Pros

    • ​Aesthetically pleasing
    • ​Better CO2 diffusion
    • ​Creates CO2 mist
    • ​Fits with cannister filters
    • ​Prevents debris on the ceramic disc
    • ​Has a check valve
    • ​Has two suction cups for easier installation


    • ​Expensive
    • ​Doesn’t work properly with filters other than cannister type

    ​6. Sera Flore Active CO2 Reactor 500 – Best Automatic CO2 System Aquarium

    Sera Flore Active CO2 Reactor 500

    Who isn’t familiar with impressive German engineering? Sera Flore Active CO2 Reactor 500 comes with the same promise of top-class engineering as other German products.

    This little reactor is one of the best performing CO2 diffusers that you can find. If you are someone who doesn’t care about the looks but the sheer performance, this is the device you have been looking for!

    This is not a beauty pageant winner but a solid heavy-duty performer that can diffuse 500 to 1,000 bubbles per minute, depending on the model you are getting. You should be getting this monster for large to very large tanks (66 to 160 gallons).

    The whole mixing process is done in the inner chamber, where the water and the CO2 mix perfectly. Later, the mixed water is fed to the tank through the hose barb on top of the reactor.

    So, you can call it a complete CO2 system for aquarium.

    Notable Features

  • ​- Water and CO2 gets mixed in the tank by the spinning paddles in the inner chamber
  • Only carbonated water enters the tank ensuring 100% efficiency
  • Intakes water directly from the filter
  • All part can be disassembled for cleaning
  • Can be placed inside or out of the tank
  • Suitable for larger tanks only


    • ​Superior build quality, acrylic construction
    • ​Quiet operation
    • ​Leak-free design
    • ​Very efficient
    • ​German manufacturing


    • ​Doesn’t look very appealing

    ​7. Fibst CO2 Diffuser for Aquarium – The Perfection of Minimalism!

    fibst Co2 Diffuser

    Although I like glass-made CO2 diffusers, I must admit that I am very clumsy myself. Till this day, I have broken two diffusers!

    So, when I heard about the stainless steel CO2 diffuser, I got very excited. Sadly, I haven’t used it yet. I am planning to use it soon (after I break the one I have right now!).

    Despite having a stainless finish, the minimalistic design is absolutely stunning. It has a tiny SS dome that is connected to a 5mm sleek SS tube.

    Rather than using a thick ceramic disc, they have used a ceramic sheet that compliments the design philosophy.

    The minimalism of Fibst CO2 Diffuser is something to die for!

    Notable Features

  • ​- Made of sturdy 304 stainless steel
  • You can unscrew the dome to clean the ceramic disc if it feels necessary
  • Ultra-durable ceramic sheet
  • A 33-inch U-bend tube allows smooth CO2 flow
  • The CO2 diffuser kit is extremely easy to install as it has a minimum amount of parts
  • Pros

    • ​Robust build quality
    • ​Easy to install and maintain
    • ​Two years warranty period
    • ​Suitable for large tanks  
    • ​Extremely good looking


    • ​None!


    What Is A CO2 Diffuser and What Is Its Purpose?

    Unlike animals, plants intake CO2 and release o2 in the environment. This statement is true for almost all kinds of freshwater plants.

    This is an essential step for the photosynthesis process. Otherwise, the plants can’t make enough food for themselves and eventually die.

    Fish and the plants in a freshwater aquarium create a co-depending environment. The fish exhale CO2 that plants intake and, in return, exhales o2 that the fish inhale.

    There shouldn’t be any problem, everything is at a perfect balance, right?


    In freshwater aquariums, especially in the smaller ones, the CO2 quantity in water might not be at an optimum level. So, the aquatic plants suffer or can’t thrive fully.

    The solution is providing more CO2 in the water. However, dissolving CO2 in the water doesn’t happen naturally or automatically. We need to diffuse the gas in the water.

    This is where a CO2 diffuser comes at play.

    The device diffuses CO2 in the water in the form of tiny bubbles, increasing the CO2 level in the tank water. Typically, these devices use ceramic discs that agitate the water, making it absorb the gas.

    Moreover, some fishkeepers find the device aesthetically appealing as it creates spectacular bubbles.

    More: Best Sand for Reef Tank

    Do I Need a CO2 Diffuser for My Aquarium?

    Having CO2 diffusers aren’t mandatory for every planted tank. However, if you are planning to have a few too many plants in the tank, you should get one.

    A CO2 diffuser will regulate the water in a planted tank very efficiently. Most probably, your plants will not die if you don’t have a diffuser in the tank, but it would help to a great extent. 

    If you want your plants to maintain the fresh, lush green color, it’s a great add-on. However, if you don’t have live plants in the tank, don’t bother getting one.

    You should get a CO2 diffuser if you –

  •    ​- Have too many plants in a small freshwater tank
  •    ​- See your plants getting flabby instead of standing strong
  •    ​- Feel that your plants are getting weak gradually
  •    ​- See your plants dying one by one
  •    ​- Have low fish count in the tank
  • More: Best LED Aquarium Lighting

    How to Install CO2 Diffuser?

    There is no single cookie-cutter strategy that you can apply for installing a CO2 diffuser. Most of the manufacturers have unique installation method that you should follow.

    That being said, no matter what I say, you should follow only the instruction manual coming with the device.

    However, there are a few things that you should know before making a rash move. You will need these two things for CO2 diffuser setup –

  •    1. A CO2 tank
  •    2. Bubble counter
  • Your first move should be filling the bubble counter with water. It should be submerged in water so that 1/3 of the device remains underwater. It will prevent the open end of the tube from sucking air.

    Next, you need to make sure that there is no leak in the O-ring. You don’t want things to be messy.

    Who wants tubes and devices poking out of the water?


    So, in the third step, do whatever you can do to hide the tubes and the bubble counter.

    The fourth step is attaching the bubble counter to the CO2 tank. While doing so, you should leave some slack. If you make the tube joints too taut, it might get loose after a while.

    You are almost ready!

    Now, it’s time for the final step. You should be ready to install the CO2 diffuser. Attach another piece of tube to install the device.

    Let me give you a big reminder; plants need CO2 only when they activate the photosynthesis process. The process doesn’t start unless there is enough sunlight or other kind of light.

    So, it’s wise to turn the device off when there is no light.

    More: Best Salt for Reef Tank

    What Is the Best Place for CO2 Diffuser?

    Well, when it comes to CO2 diffuser placement, it all comes to your creativity and vision.

    Still, you could follow some tips so that you can reap off the optimum result from your CO2 diffuser.

    The most obvious tips would be placing the device close to the bottom of the tank near the substrate level. In this way, you can increase the contact time between the CO2 bubbles and water.

    However, don’t make the mistake of placing the diffuser at the substrate level. The gravels will block the miniature holes in the ceramic disk. As a result, the tiny bubbles will accumulate and create larger bubbles.

    It will diminish the actual purpose of installing the diffuser.

    For the same reason, you shouldn’t place the diffuser beneath the plants.

    The diffuser should be in an open place somewhere near the bottom of the tank. Don’t try to be too creative here.

    There is a witty trick that you can follow. If you place the diffuser close to the water filter, the bubbles will travel across the tank, taking the maximum time.

    Okay, what if you can’t place the diffuser close to the filter? What should you do?

    You should place it somewhere that will make the bubbles catch up with the current.

    Furthermore, you should trim down the plants regularly. It will increase the free-flowing area for the water.

    More: Your Guide to a Peacock Cichlid


    Gather round folks; it’s time to hand over the prizes!

    Guess who’s the winner today?

    Yes, the first prize goes to JARDLI Pollen Glass CO2 Diffuser with Bubble Counter. Then, comes Fibst CO2 Diffuser for Aquarium for its amazing design philosophy.

     I was very confused about the third place.

    Still, after a while, I made up my mind. The third-place award goes to Sera Flore Active CO2 Reactor 500 for the superior build quality.

    What do you think about these products?

    Let me know in the comment section.

    More: A Guide to Choose the Best Koi Food


    • William Rieder

      Hi, my name is William Rieder and I'm a pet and animal blogger. I love reviewing all things pet related, from dogs to cats to horses! I also write about other topics such as personal finance and relationships. I enjoy helping people find the perfect pet for their lifestyle and am always interested in hearing what they have to say about their pets.

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