A CO2 diffuser is responsible for spreading carbon dioxide throughout your tank, as the name implies. Instead of concentrating all of the CO2 in one place, it helps to spread it evenly and thoroughly. It must be combined together with CO2 regulators, CO2 reactors, and other CO2 equipment to create a complete CO2 system for your planted tank.
As bubbles rise from the diffuser, you can watch the process in action. Instead of vast pockets of CO2, the best CO2 diffuser will inject tiny bubbles that diffuse way better than larger bubbles. The gas then, when it comes in contact with another surface it gets distributed in the water. As a result, a smaller stream of bubbles will be more effective than a bigger stream of bubbles.
Small streams discharge far more gas into the system, making them more likely to absorb the water. This article will teach you all you need to know for an aquarium air diffuser, from learning what it does to the top products in the market.
Things like the placement of CO2 diffusers in aquarium walls are essential to the way everything works, so be mindful of everything and consider all points before making your purchase and then using it. Who knows, by the end of this, you might even get the proper knowledge to build your DIY CO2 diffuser.
- Best Overall: Fibst CO2 Diffuser
- Best Inline: NilocG Aquatics
- Best Budget: TWINSTAR CO2 Diffuser
- Best Ceramic: Yagote CO2 Glass
- Best 3-in1: Tropica CO2 Diffuser
- Best for Deep Tank: Aquario Neo Co2 Diffuser
- Best for Nano Tank: Fluval co2 diffuser
Best CO2 Diffusers Reviewed
The list below was a result of years of experience and knowledge that brought together these hand-picked products from all around the market right to your fingertips.
If you would describe yourself as clumsy, then look no further for a great choice. This Fibst CO2 diffuser made of sturdy material should be just perfect for you. It comes in three sizes, each suitable for tanks from ten to thirty gallons.
Its build features a ceramic disc placed inside an open-top dome which you only need to unscrew for easy access into the disc whenever you need to clean it or replace it. The construction made of stainless steel makes it way more durable than glass.
Right below the dome, the tube takes a J- curve of 13 inches, curving then back, forming a U-bend and hooking over the side of the tank. However, this makes it unsuitable for pairing with DIY systems and that its height is not adjustable. Another important detail is that the product has no bubble counter or check valve.
However, the factor pushing this product forward in superiority is the warranties it offers designated for each specific part. The diffuser comes with one six-month warranty on the ceramic disc and another 24-month warranty for the other parts. This product was so good; we awarded it the best CO2 diffuser for the planted tank (or any tank for that matter).
Sometimes beauty isn’t perfect, and we want to prove that to you through the following product. NilocG Aquatics Atomic Inline CO2 Atomizer Diffuser comes in various sizes and fits just about any freshwater tank.
You might find it a bit pricey, and it would be good to inform you that you might find the product willing with water and sometimes failing when the solenoid cuts off; however, it is not this delicate in every aspect.
The piece is super simple to install, and you can easily mount it below or directly to the aquarium. Cleaning this product is also a no-brainer task. All you need is a water/bleach solution and zero fear of mishandling it as it is very tough to break.
The secret behind this relatively cheap CO2 diffuser is that it utilizes a ceramic stone with microspores to produce super tiny bubbles that last way longer, making the solubility efficiency of CO2 increase.
The body is made of transparent acrylic giving it more durability on products made of cheaper glass that turn the simple task of cleaning it into a nightmare. Taking into consideration its smart fix for small harmless bubbles and guaranteed durability, this piece can reliably withstand high pressure.
The model is available in small, medium, and large sizes, fitting for tanks up to 65 gallons.
Look no further to find the perfect diffuser to produce rich CO2 for your aquatic plants than this ceramic masterpiece. It will ensure your hydrophytes’ needed nutrition and overall health and help provide a friendly habitat for the plants in your tank.
This CO2 diffuser utilizes atomic pores on the surface of its disc to ensure the production of fine bubbles, which move slowly and diffuse the CO2 efficiently in the aquarium. The quality of the glass material is also guaranteed, so you need not worry about damaging or breaking it.
This choice is also incredibly practical because it includes a suction cup which makes it easy to install the diffuser, fix it onto the tank and operate it. The glass reactor is fitting to pair with tanks from 15 to 50 gallons. Featured in the package also comes a Glass 3 Spiro CO2 diffuser.
Tropico CO2 Diffuser is a practical, all-in-one diffuser with a bubble counter. The counter behaves as a regulator of CO2 dosage, given that it makes it easy to count giant bubbles during the process of adjusting. The built-in reflux valve doesn’t allow the counter to run out of water should the CO2 supply be suspended.
With this product, it is recommended to apply a thin layer of vaseline on its suction pads for safer and ensured adherence.
A role of thumb to always keep in mind is that working pressure of minimally 1,8 bar is necessary for the proper functioning of the diffusor. We recommend you only run the atomizer on a regulator of pressure, which enables you to customize the pressure to your personal liking.
You will know it’s time to clean when algae start forming upon your glassware, and you start seeing bigger bubbles come out of the diffusor. Glassware needs to be handled diligently, but it is nonetheless super easy to clean with chlorine bleach without perfumes at home.
Next up, our top pick for deep tanks is the Aquario Neo CO2 Diffuser, which features an extra-long pipe that can be easily individualized through a special heat technique. It makes your whole setup look tidy and organized by getting rid of messy dangling hoses.
The membrane of ceramic material produces fine mist and ensures the quick dissolving of CO2. The diffuser in itself is not very wide and is flawlessly connected to the pipe on its side.
Application of the product is innovative: you can experiment with either of the two 16 cm acrylic pipes included in the package simply by hearing them up until they soften and then shaping them quickly to preference.
The following product is subject to an exciting design: a round plastic body around a ceramic disc. The whole thing resembles a donut on top of which a small nipple attaches the CO2 line. It can all be attached to the side of your aquarium with only a suction cup; that is easy! This model is one of the best choices for your nano aquarium.
It may not be the most aesthetically pleasing piece, but its modest looks aren’t that important, seeing how easy it is to use this product and how small and neat it fits into the tank. While most diffusers might win any beauty contest, this one is sure to snatch the gold medal of practicality.
Types of CO2 Diffusers
The catalog for CO2 diffusers seems endless, but we promise you once you learn about some minor technical terms, it will be a breeze figuring your way around.
Diffusers vary in many different aspects such as size, price, features, construction, and price. Luckily there are only three types you will need to memorize because of their popularity, and they are as follows.
Ceramic CO2 Diffuser
Typically, a ceramic CO2 diffuser resembles a thin ceramic disc or membrane, often protected by an exterior rim of a glass or stainless steel. The middle of the disc houses a ceramic layer that transforms, bypassing CO2 into tiny bubbles.
CO2 diffusers made of ceramic come in a wide variety of shapes and builds, which is very convenient as it creates a lot of possibilities for you to find just what you need following your specific tank. Whether you prefer a version which you would none outside of your aquarium or you’d rather have a piece sitting inside it, this option has it all.
Let us not forget to mention that these diffusers are super affordable, which comes in handy for beginners who wouldn’t fancy breaking the bank over a significant investment of overwhelming equipment.
In-line CO2 Diffuser
If aesthetics and visual presentation are your priority in your setup, in-line diffusers could be your best option. These pieces directly hook into the canister filtration systems, are powered by your filter’s motor, and can usually be hidden, thus minimizing the mess inside the aquatic environment.
However, they do prove to be harder to calibrate, especially when paired with larger tanks, and they need to have a good filter flow rate by their side to perform optimally if used on the outflow line.
In-line CO2 diffusers are more efficient than ceramic ones, yet not as effective as CO2 reactors. If CO2 mist is not your thing, you may just have found your best option.
Airstone Diffuser
Coarse stones used to increase water oxygenation in a tank are the same as Airstone CO2 Diffusers. However, these products do appear to be not very efficient, better to keep them with the air pumps.
How to Choose the Best CO2 Diffuser
There are some key factors you need to take into account before you choose the best CO2 diffuser. When summed up together, these factors also bring us to the conclusion of which device is definitely the best for your aquarium CO2 system.
You need to be quite selective when choosing your brand-new CO2 diffuser as it is vital to maintaining a happy and healthy aquatic environment. Ensuring that you are working with a high-quality product always saves you time and is uncompromising.
Quality
Whatever you purchase, its quality is critical. In this case, there really is no good in negotiating or making compromises with the product’s price because typically, the lower the price, the lower the quality. On the other hand, a massive price tag doesn’t always make for high-quality pieces either.
Lower quality CO2 diffusers tend to experience leakage, are a pain to monitor and regulate, and will end up being more frustrating than anything else.
Compatibility
You always need to ensure that, whether you have an existing system or are making your first-time purchase, your precious CO2 diffuser is compatible with the rest of your equipment. Given that CO2 diffusers vary in inlet and outlet sizes, you may be faced with the need to change your tubes.
Some specific models may sometimes be incompatible with lower or higher levels of the dispersion of CO2.
Of course, you also need to consider the future of your aquatic environment. For that reason, it might be a more intelligent decision to go with a more reputable brand when purchasing the CO2 diffusers so you can find replacement parts more easily.
Accessories
As we touched on earlier, specific types of CO2 diffusers might require extra parts and accessories. In the case that your setup is brand new, a kit including everything you need can prove to be the most money-and-time-saving purchase you make.
Apart from that, it just feels much better to have all you need in one package than looking for tiny pieces in a thousand different places, which can even end up being completely dysfunctional.
Appearance
When your goal is to build a healthy aquatic environment that looks neat, you might want to pick a CO2 diffuser that won’t hang out the tank like a wonky limb.
Of course, a functional CO2 diffuser looks cool and blends in with the overall look of the setup. That should only take very little consideration.
Kit Inclusions
Sometimes, bits and pieces included in the kits can really be the deal-breaker (or maker) in the performance of the CO2 diffuser. Some come with equipment such as U-bends, check valves, and bubble counters.
Understandably, you might just not feel like spending a ton of money on things that seem tiny, but you need to understand that some equipment, however small they may seem, are necessary, and you might need to purchase it separately.
Additional pieces and equipment tend to be very inexpensive; however, it’s always best to know as much as possible.
Size of the Aquarium
It is important to always factor in the size of your aquarium while you’re in the process of finding the best CO2 diffuser. Fortunately, there is a massive catalog of flexible CO2 diffusing devices you can install into small and large aquariums.
They do, however, tend to be on the pricier side. Don’t get discouraged just yet, because you can always find a more affordable item, especially if you have a small tank.
Quality and Materials
Truly most CO2 diffusers available are made of stainless steel, but you can find a good number of them that are made of acrylic glass or plastic. However, your final decision should always fall in line with the inlets and outlets of your filters.
Stainless steel or glass is usually what filter inlets are made of so logically, why not go for a CO2 diffuser of the same material? Well, for starters, these options usually feature extremely fine-pored membranes.
Membranes are an accompanying part of acrylic glass and plastic CO2 diffusers; however, their membranes are tons more adorable than glass or steel devices. Models of acrylic glass are increasing in popularity due to their aesthetically pleasing design, whereas those of plastic tend to have a bad rep for the opposite of that reason.
Our Verdict
By now, it’s safe to say that, however big and scary the market may feel, we got your back into handpicking with utmost care the best CO2 diffusers for you. Well, this is it. These are our top picks for your every possible need.
Whether you choose to go for the safe overall choice and decide to purchase the Fibst CO2 Diffusor or you have more specific requirements such as the size of your tank needing to be compatible with your choice of product and go with the Fluval CO2 Diffusor instead, we are sure you will find yourself here.
Despite your personal preference and specific requirements, every product on this list is the best at its job, guaranteed by our dedicated team that continuously strives to bring forward only the best options for your absolute convenience.
Best CO2 Diffuser Placement
Many people have aquariums but don’t know where best to put the CO2 diffuser in an aquarium. There are a few best practices that you should follow when placing your CO2 diffuser in your fish tank, so I’m going to cover them now.
Where to Position a CO2 Diffuser?
CO2 diffuser should be placed at the middle of the flow provided by the aquarium filter or powerheads. If bubbles rise vertically, the flow pressure should be that strong to push them down the tank and carry them to the next corner of the tank.
When setting up your CO2 diffuser, you want every bobble to be released and stay inside the tank. Your goal is to put your CO2 diffuser as deeply in the tank that none of the bubbles would make it to the top of the water. You can try and experiment with the placement of the diffuser.
Our best suggestion would be to leave it under the outflow of the hang on back filter or an aquarium powerhead. The flow will push the baubles down, giving them more time to dissolve.
