[Latest 2021] Top 10 Best Aquarium co2 Diffuser For Your Aquarium Plants

Getting enough CO2 in a planted aquarium can be tricky. This is why using the best aquarium CO2 diffuser is essential for plants to thrive.

If you want to have a live, densely planted freshwater aquarium, you need to fertilize your plants with carbon. Carbon is not easily replenished in liquid or solid form like other fertilizers and is generally supplied as gas. To efficiently mix carbon dioxide gas into your aquarium water, you need the Best Aquarium co2 Diffuser.

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They are designed to add the right amount of CO2 quickly and easily and are generally inexpensive and easy to install.

Top 10 Best Aquarium co2 Diffuser for Your Aquariums

Best Aquarium CO2 Diffuser Reviews

1. Pm0606 Micro CO2 Bubble Diffuser

Best Aquarium co2 Diffuser

This CO2 diffuser is a good choice if you are looking for something that produces micro-fine bubbles. Micro bubbles help disperse CO2 quickly, making it readily available to your plants.
This diffuser is made of sturdy glass that does not break easily. It is also washable and can be used over and over again without having to replace it.

Part of the reason this diffuser is so effective is because it is so light and airy, which is why it can produce so many fine bubbles. It is cup-shaped and has a large surface ceramic disc for greater effectiveness.

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2. JARDLI Pollen Glass CO2 Diffuser with Bubble Counter

Best Aquarium co2 Diffuser

The JARDLI CO2 diffuser is a great choice if you are looking for something to match your tank. It creates little bubbles that look great in your tank, while giving your plants an easy way to absorb what they need to grow. The ceramic membrane has a large surface area and is therefore able to create so many bubbles.

This is a small diffuser, only 0.8 inches, and is designed for use in tanks under 20 gallons. It is compatible with 4/6mm CO2 tubes and is made of high quality materials including glass and ceramic membrane.

To make sure everything is working properly, wet the glass tube before attempting to connect any tubes. This acts as a lubricant and the tube slides without risk of damage.

Also ensure that the ceramic disc, tube and other surfaces are soaked for at least 30 minutes before use.

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3. fibst CO2 Diffuser for Aquarium

Best Aquarium co2 Diffuser

This diffuser is a little different from the others we tested, as it is made of stainless steel instead of glass. Stainless steel does not rust or corrode and will therefore last a long time in your aquarium.

It also adds a simple and elegant piece of art to the environment. Produces fine, round bubbles as opposed to partial bubbles created by other diffusers.

Cleaning is easy, just turn the stainless steel mug to remove the ceramic blade cover. Installation is also a breeze, just hook the diffuser over the edge of the tank and use the stainless steel fitting to secure it.

Another great thing about this one is that it comes with a pretty impressive warranty. You get 6 months for the ceramic plate and 24 months for the other parts.

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4. JARDLI Music Glass CO2 Diffuser for Aquarium Plant

Best Aquarium co2 Diffuser

This JARDLI CO2 diffuser is designed for large tanks of 75 gallons or more. The cool, artistic look isn’t obtrusive and doesn’t detract from the aesthetics of the tank, but still adds a bit of movement and visual appeal.

The large 2-inch diameter and ceramic membrane create a broad mist of tiny CO2 bubbles. This is very important because it is much easier for the smaller bubbles to diffuse into the water, making the CO2 usable for your plants.

It comes with two suction cups for easy installation and the diffuser itself is made of high quality borosilicate glass which is very strong and durable. The construction is excellent and makes a great addition to any large plant aquarium.

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5. STARSIDE Aquarium CO2 Diffuser

Best Aquarium co2 Diffuser

Made of high quality material, this STARSIDE CO2 diffuser features a U-shaped design to match any countertop. Because it is made of resin and not glass, it is more resistant to bending and extremely durable.

It uses a ceramic disc that produces a steady stream of tiny bubbles that easily diffuse into the water to benefit your plants. Installation is also easy, just use the suction cup to attach it to the side of the exhaust and adjust the U-bend as needed.

One of the best things about this design is that it’s very understated. The U-shaped section fits easily over the side of most rimless tanks and some tanks that also have a rim. If the U-shaped part does not fit, the rest of the diffuser still works with a simple tube.

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6. Yosoo U-Shape DIY CO2 Diffuser

Yosoo’s U-shaped CO2 diffuser is easy to install and operate. Use the included suction cup to attach it to the side of your tank and connect it to your CO2 source. The small see-through design is easy to hide so it won’t distract from your tank setup.

We like this one very much because it is multifunctional. Not only is it an atomizer, but it also acts as a check valve, bubble counter and U-shaped air inlet. The U-shaped gasket makes it very easy to set up the tube and the bubble counter is accurate and works well. .

The check valve is always handy and the aerator produces bubbles of the correct size for diffusion. This is a simple design that is highly effective and ideal for small to medium sized aquariums.

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7. Hagen Fluval Ceramic CO2 Diffuser

The Fluval Ceramic Diffuser has a round plastic housing around a ceramic disc. It looks like a little black donut or tire. A small nipple protrudes from the top of the donut to which the CO2 pipe connects.

Everything can be attached to the side of the tank with a suction cup.

And that’s it, it really is that simple.

It’s nice that this diffuser is easy to install and doesn’t break easily, but if I’m honest it’s pretty ugly. Most diffusers look great, but this one looks like a strange piece of plastic in the tank.

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8. Aquario Neo CO2 Diffuser L

The Aquario Neo is unique in this list because it is the only diffuser that works with a do-it-yourself system. The membrane is so porous that it will bubble even at low pressure.

The diffuser housing is made of clear acrylic which is much more resistant to breakage than glass. The folks at Buce Plant even threw the diffuser on the floor and it still didn’t break.

Since I’ve seen reviews of people complaining that their glass diffuser broke after a 6-inch drop, I’d say it’s a huge improvement.

I’ve even seen reviews of glass diffusers breaking while still in the aquarium. So I like one of harder material.

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9. Fluval Ceramic CO2 Diffuser

If you are using the Fluval brand pressurized CO2 system in a small aquarium with a capacity of less than 30 gallons, the ideal replacement is this small ceramic diffuser from Fluval. With its large ceramic disc, this diffuser produces a constant stream of fine bubbles. It’s easy to install, and while it’s not the prettiest device, it gets the job done. It is also a very cheap replacement part, which is handy. It is perfect for Fluval systems and will work with most pressurized CO2 generators as long as they produce at least 30 psi (pounds per square inch). This is a very basic diffuser and comes with some protection for the ceramic disc and a suction cup to hold it in place.

However, it is not my favorite diffuser, not even for Fluval CO2 systems. The diffuser is not very easy to clean and the ceramic disc cannot be removed from the housing. While you can soak everything in bleach or hydrogen peroxide to remove any stains or algae, the fittings seem to wear out quickly and this diffuser needs to be replaced regularly. The Fluval is harder to break than glass diffusers, so for some users it may be a more durable and cost-effective option. Even if you have to replace it more often because of its marginal quality, it probably won’t break if you remove it for maintenance.

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10. Sera Flore CO2 Active Reactor 500

If you want the best CO2 reactor, this model from Sera is considered the top model for smaller aquariums. It is the ideal size for a planted tank under 160 gallons and works with pressurized and low pressure CO2 injectors. With two impeller blades, the Sera can spread up to 500 CO2 bubbles per minute in your aquarium. The Sera can be installed in-line as part of your container filtration system, or you can use it with a pump in your aquarium. This flexibility allows you to position it in the optimal location based on your tank flow patterns and the location of your inlet and outlet lines.

CO2 reactors are significantly more efficient than other designs, so if you want to ensure that most of the CO2 in your system is available to your aquatic plants, using a reactor is the way to go. This is an ideal reactor for tanks from about 50 gallons, but will likely be a waste if installed in smaller planted tanks. Like all CO2 reactors, the Sera makes a lot of noise immediately after installation or maintenance, because air bubbles need time to escape. This isn’t the easiest diffuser to install either, but Sera has top-notch customer service and they are very helpful if you have any problems. I would definitely choose this diffuser over any other on my list if it’s right for your tank.

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What is a CO2 Diffuser and What is its Purpose?

Aquarium plants absorb carbon dioxide and give oxygen to the water. That said, they need more carbon dioxide to thrive than is available in most freshwater aquariums. That’s where a CO2 diffuser comes in.

Since CO2 is a gas, it takes some effort to dissolve it in water. Just bubbling won’t provide the levels plant life needs to thrive. Diffusers work in part by increasing the surface area of water exposed to the gas.

This is generally achieved by passing CO2 through a ceramic disc. This agitates the water and keeps it in contact with the CO2 for longer, allowing it to be absorbed more efficiently.


How to Choose Best CO2 Diffuser ?

Start with your tank mate

Size matters when it comes to CO2 diffusers. A diffuser designed for 10 gallons is not big enough for 55.

The surface of the ceramic disc will not be large enough to suck up the amount of gas you need for that much water.

A smaller diffuser is also not designed to handle the higher pressure required for a larger tank.

On the other hand, when using a diffuser designed for a larger tank, lower CO2 pressures may not be able to push the gas through the ceramic disc.

That is why it is important to buy a diffuser that is appropriate for the size of your tank.

Think about the overall quality

With a lot of aquarium equipment, you get what you pay for. CO2 diffusers are no different. Yes, it seems that some diffusers cost a lot more than others when you’re shopping.

But if cheap doesn’t work so well, what good is it? CO2 is not free, so having a diffuser that doesn’t distribute it well through the water is a waste of money.

Sometimes you need to consider usage costs over time rather than just price.

Honestly, I’d rather pay a little more upfront if it works better and lasts longer.

What does the kit include?

Some grilles come with additional equipment such as U-turns, bubble counters and/or check valves.

If you base much of your choice on price, it’s important to consider whether you need to purchase additional equipment.


Best Place to Put a CO2 Diffuser in Aquarium

There are a few things to keep in mind when it comes to fitting a CO2 diffuser for optimal results.

First, it should settle near the bottom of the tank. The longer the bubbles stay in contact with the water, the more it will be absorbed. You may be tempted to place it under the ground, but this is not ideal. Why?

Because the surface of the ceramic disc that releases the bubbles is somehow blocked, the bubbles will not keep their small size. They accumulate and collect in the larger bubble, which is not absorbed as effectively.

You should also avoid placing it between plants. While it may seem like this would be a good place to do it, as it benefits plants in the first place, it can cause problems. On the one hand you run into the same problem as with the substrate, causing the bubbles to collect on the plants and mix into larger bubbles.

Remember that the goal is to circulate the CO2 bubbles as much as possible so that they have as much time as possible to absorb. A good place to place it is under the filter return. That way, the water returning to the tank will push the bubbles down, which is one way to keep them circulating longer.

If you can’t place your diffuser that close to your filter, try placing it in a location where air bubbles are trapped in the flow created by the filter return. Again, this keeps the bubbles circulating and prevents them from rising to the surface too quickly.

Another thing to remember is that you may need to move the diffuser as plant life begins to grow. When the plants get bigger and denser, the flow of the water will be affected and you may encounter the same problems we mentioned above, the bubbles build up and get too big and then quickly escape to the surface.


How to Install a CO2 Diffuser?

The installation will be slightly different depending on the model you are installing, but here are the basics.

First of all you need a CO2 tank. It is also highly recommended to use a bubble counter. Fill the bubble counter tube â…“ out of the way with fresh water and keep the open end of the tube submerged so no air is drawn in. Make sure the o-ring is tight so there is no leakage.

Mount the bubble counter on the side of the tank or on the wall so that it is easily visible. Then cut the hose to connect the CO2 tank to the bubble counter. Leave a little slack, you don’t want this fit to be too tight.

Then connect the bubble counter to the CO2 diffuser with another length of tubing. Make sure you use enough hoses. Again, you don’t want it to be tight and you want it to be long enough to ensure the position is correct. After they are connected, place the diffuser in the tank.

Keep in mind that plants only absorb CO2 through photosynthesis, so they need sunlight or another light source. When it’s dark they actually give off CO2, so the diffuser shouldn’t work when the light is off.


FAQs For CO2 Diffusers

Where do you place your CO2 diffuser?

You should place your diffuser where the most power is in your tank. This will help distribute the bubbles throughout the aquarium and help dissolve the CO2 in the water.

If you place the diffuser in an area with little or no flow, the bubbles will go straight to the surface and escape. You want to keep the bubbles under water for as long as possible so that the CO2 has a chance to dissolve in the water.

How do I install a CO2 diffuser?

There are MANY different CO2 diffusers on the market and the installation of the different models may be a little different. But here are some general guidelines.

I go along the line from the CO2 tank to the aquarium.

The first device after your CO2 tank should be your check valve. This prevents water from flowing back into your CO2 tank when the pressure drops, for example when the power is turned off at night.

The next device should be your bubble counter (if you are using a separate device). This lets you know how fast gas is being fed into the system, so you can increase/decrease the pressure and adjust the amount of CO2 pushed into the aquarium.

Next comes your U-bend. This is important because CO2 hoses can harden over time and bend where it bends over the edge of the tank.

The diffuser is the end of the line. You want to place it as low towards the bottom of the tank as possible. It’s totally fine if it’s just above the gravel. You want the bubbles to spend as much time underwater as possible.



In order for freshwater plants to thrive, most aquariums need extra CO2. The only way to add it effectively is with a CO2 diffuser. By using the Best Aquarium co2 Diffuser, your plants will have everything they need to thrive.

Jesse B.

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