7 Best CO2 Diffusers and Reactors for Planted Tanks

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If you bought yourself a fish tank, you probably added all sorts of plants inside it, besides the traditional fish. That is usually how an aquarium works. However, if your tank is well-planted, you might need to use certain devices to help your plants live longer and healthier in the aquarium.

This is where a CO2 diffuser and reactor will come into the picture. How? These devices are needed to help add CO2 into the water. As you know, CO2 is used by plants to stay alive. Differently from us humans and most animals (fish included), plants need CO2 to photosynthesize. In this process plants will produce oxygen and will release it into the water.

A small amount of CO2 is always present in your tank, because fish will breed in oxygen and will breed out CO2. Though, this amount of CO2 is not enought for some plants. That is why you need to use a device that helps diffuse it to your tank.

In this article, you’ll learn about the best CO2 diffusers and reactors, used for planted tanks. Any of the items I’m going to talk about, are present on the official Amazon website, so you won’t have any problems finding them.

Also, later in the article, I will help you know more about CO2 diffusers, and how you can choose a winner for yourself, from these items. You will find out how to measure the CO2 level in your tank as well.

Before I jump into more details about CO2 diffusers and reactors, I highly recommend reading my other article, in which I talk about how dose liquid CO2 in your planted aquarium.

1. Jardli Pollen Glass CO2 Diffuser

The first product on our list comes in 2 different versions:

  • One for a 50-gallons tank
  • Second for a 75-gallons tank

In this article I’m going to talk about the second item, that works with aquariums up to 75 gallons in capacity. It uses a ceramic membrane, through which it efficiently atomizes CO2. The membrane is 2 inch in diameter, which is more than enough for a 75 gallon fish tank.

A U-shape connector tube is added into the package, that will prevent the blockage of the CO2 flow through the membrane. Besides this connector tube, there are 2 suction cups included as well, which play a part in easily setting up the diffuser inside your tank.

The CO2 will easily dissolve in the water, due to the large surface to volume ratio of the membrane. This is highly recommended, because the CO2 will get used up by your plants much faster and easier.


2. NilocG Aquatics Intense Atomic Inline CO2 Diffuser

This device is the second on our list, and we recommend it for beginner and experienced fish keepers as well. It comes in 2 different versions, for different tubes. The second one is better if you want a high performing device in your tank.

This works as a 5/8” tubing, which will results in a high rate of CO2 diffusion. Also, the CO2 will leave the tube as small particles, that will get dissolved in the water much faster, too allow a better environment for your plants. Actually, the product promises 100% of CO2 dissolution in the water.

The design is very handy, because you can use it together with a canister filter. This is great news, meaning that you don’t have to buy a full set of parts for it to work, if you already have a proper water filter set up (which is quite likely).

The installation is simple and quick, without the need of any technical knowledge. You just have to mount it below or directly onto the aquarium, using your canister filter.


3. Fibst CO2 Diffuser

Like the previous devices, this one also comes in multiple versions. The best though is the 3rd item, called 30Dx350L. This means that it will easily work on aquarium of 350 liters in volume.

It’s worth mentioning how this device can produce all-round bubbles when diffusing CO2 into the water. This is important, because most other item on the market can only produce partial bubbles, that don’t do as much good as these.

The product is made from stainless steel, to resist a long time of usage. It looks elegant, and it won’t destroy the look and feel of your aquarium. Also, with the stainless steel tube, the device is very durable, and not as fragile as other glass products.

In the box, you’ll get the device itself, 1 stainless steel fixing system, a 6-month warranty for the ceramic sheet that emanates CO2  into the tank and a 24-month warranty for the whole device, included every other part that comes into it.


4. Jardli Glass Inline CO2 Atomizer

Here’s another Jardli product, but one that is a little different from the previous one listed. This is an atomizer, made of glass, used in all sorts of fish tanks. I’m mentioning the second variation of the product, because works with even bigger fish tanks, used by more experienced fish keepers. However, small tanks are not exception here.

This atomizer will dissolve the CO2 in the water using turbulent mixing, which will increase the saturation of CO2 in the aquarium’s ecosystem, thus resulting in better plants. To further enhance plant growth, it creates a fine mist of CO2 in the water.

It also reduces photosynthetic algae growth, due to its inline mounting system. If you place it away from direct light, you can further improve this feature.

Just like with a previous item, this atomizer also works with a canister filter, that you may already own. Just install it on the outflow tubing of the canister filter, either below the tank, or mounted on the outside wall of the aquarium.


5. Sera Flore Active CO2 Reactor 500

This device is a CO2 reactor, as its name suggests. It works with smaller and bigger fish tanks as well. However, you need an aquarium that’s at least 66 gallons in volume, to be able to make use of this reactor. But the good thing is, it will work perfectly with fish tanks up until 160 gallons in capacity.

If you use it properly, it will result in full CO2 dissolution in the aquarium water. You can mount it in the tank directly, or besides it, if that’s better in your personal case.

It can dissolve 500 to 1000 CO2 bubbles per minute. Of course, this number depends on the model you’re buying. For a larger tank, I recommend one that dissolves close to 1000 bubbles per minute, to ensure a better CO2 concentration in the tank.

It includes hose connectors, suction cups and brackets for an easy installation. The acrylic fabric is a durable material, which they used to create this product, meaning it will do its job for a long time after purchase.


6. Mr. Aqua CO2 Aquarium Turbo Diffuser 600

The Turbo Diffuser is a top quality product that will work perfectly with aquariums of up to 150 gallons in volume. This one comes in only a single version, but that’s really all you need. It will work well with both small and big fish tanks, no matter your case.

Due to its small and compact design, you can easily place it besides your aquarium, without ruining its look. Of course, it will not only look good, but work efficiently. After all, that is the reason for buying such a device.

You can set it up very easily, probably the easiest installation among all the 7 products I listed in this article. That is why I highly recommend this item for total beginners. Also, you should know that among the rest, this device is quite cheap, so it’s not a lot of investment to get for yourself. This way, you can test if such a device is what you need for your aquarium.


7. Yosoo CO2 Diffuser

This is our last item on the list. Being last, doesn’t mean it’s any worse than the rest. You can be confident that any of these devices will work as they should, and the Yosoo is no different here.

This device is an atomizer for CO2. It’s made of high quality and durable materials, that are also eco-friendly and safe for your fish and plants inside the aquarium. You will set it up easily, without much fuss, and using it is even easier than that. It comes with a safe nut locking system, that prevents the tube from loosening and breaking the dissolution process.

It works by putting in practice osmosis technology, to diffuse CO2 into the water. This technology can greatly increase the dissolution effect of the CO2, and also save the usage of CO2, to be more friendly to the environment. Its effect on your aquarium will be felt from the first days you started using it, especially when you take a look at the plants.

Now that you know about the 7 best CO2 diffusers and reactors, it’s time to find out what type of diffuser you should choose for yourself.


What Types of CO2 Diffuser to Choose?

To answer this question, you should think about multiple aspects regarding your personal needs. For instance, your tank’s size plays a huge role in choosing the best type of diffuser for yourself. Why?

Because different models are designed to work with tanks that are totally different in size. One that performs well on a small tank, could not do so well on a big one. That is why taking your tank’s size into consideration is so important.

For a big tank, the Sera Flore Reactor I talked about above, is a great choice, for instance. However, if you have a small aquarium, the Mr. Aqua Diffuser is more than enough to handle your needs.

Besides your tank’s size, think about what you want to add inside it. If you don’t want to ruin a specific look, then a diffuser that works using directly your canister filter is better, than a traditional one.

That is because you won’t put a huge part of the device inside your tank, and maybe even bother your fish. But if you don’t care about this, or a nice traditional CO2 diffuser would look great in your tank, then go for it.  The look is really up to you to decide.

Choosing a CO2 diffuser also depends on your fish that live in the tank. If some of them, or most, have trouble if they come in contact with CO2 bubbles, then don’t use a traditional CO2 diffuser. Instead, go for one that uses your canister filter to diffuse CO2 into the water.

Do You Need to Clean a CO2 Diffuser?

A normal CO2 diffuser should be cleaned from time to time. The products I listed above, have precaution mechanisms, to prevent CO2 or other particles getting stuck on the ceramic membrane. However, even the highest quality product will sometime need cleaning, because in a tank, there are all sorts of particles floating around.

How to clean such a device? First of all, know that an in-tank CO2 diffuser should be cleaned every 2 or 3 weeks depending on how much particles have settled down on it. Also, algae are another problem that will stick to it, even while using a good water filter.

However, cleaning the device is quite simple. If you use a ceramic membrane device, like the first on the list, you can use this:

Mix a solution of 3 parts water and 1 part bleach. Leave the diffuser soaked into the mixture for about 30 minutes or so. When that much time has passed, you must take it out, and rinse it with clean water carefully.

Keep in mind: do not ever rub or touch the ceramic membrane of the diffuser. It’s the most crucial part in the process. Also, be sure you rinsed with enough water, so it won’t have any bleach left on it. That’s all. Now, you can place it back in its place.

If you own an inline CO2 diffuser, that shouldn’t be cleaned too often. It is recommended to clean it every 6 months, because it works a little differently than the previous version I just talked about.

Something worth taking into consideration is this: to make the most out of a diffuser, it is recommended to keep 2 at home. This way, you can rotate cleanings, and avoid downtime in the CO2 diffusion process. Also, the diffusers won’t get used up too quickly either.

How to Measure CO2 Level in Your Tank?

How to Measure CO2 Level in Your Tank?

How to Measure CO2 Level in Your Tank?

One of the most popular ways to measure CO2 levels in your aquarium, is to use a bubble counter. However, there is a better way for this, one that is permanent, and doesn’t need your all time attention.

You can use a drop checker. What is such a device? A drop checker is made of glass and it’s filled with an indicator fluid. The color of the fluid will show you the level of CO2 in your tank. If the fluid is yellow, it means your tank has too much CO2 in it. The blue color will indicate that there’s too little of it in the aquarium. When the fluid has an intense green color, it indicates that the CO2 concentration is just perfect.

The best thing about such a product, is the fact that you only need to set it up once. After that, you just have to take a look at it, and you’ll notice if the CO2 level in the aquarium is good or not.

The Glass co2 Drop Checker on Amazon, is a great product, that works just as I described above. This is a high quality drop checker, that works on all sorts of aquariums. It’s very simple to use, and set up. All you need to install it, is a suction cup (included in the box).

The solution that will show you the CO2 levels in the tank, is also included in the package. Before setting it up, you have to put the fluid in the container and just place it in its spot using the suction cup they added.


In this article we talked about CO2 diffusers for personal fish tanks. As you learned, such a device is needed, when your tank is well-planted, because plants need more CO2 to live and grow in the water.

I listed the best CO2 diffusers you can find on the market. To make a good choice, you should think about your personal needs, before anything else. Also, consider the aspects I mentioned above in the article, like your tank’s size for instance.

If you do all these steps, you’ll surely make a good decision, and buy a diffuser that will help you grow your plants faster.

Author Image Fabian
I’m Fabian, aquarium fish breeder and founder of this website. I’ve been keeping fish, since I was a kid. On this blog, I share a lot of information about the aquarium hobby and various fish species that I like. Please leave a comment if you have any question.
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