June 13, 2023
Best Aquarium CO2 Kit | 2022 Guide

Best Aquarium CO2 Kit | 2022 Guide

If you are looking to establish a planted aquarium, a CO2 system should be an essential component of your setup. As with all animal and terrestrial plant life, aquatic plants require a constant supply of carbon dioxide in order to photosynthesise and thrive. However, plants housed within an aquarium can struggle to access sufficient levels of CO2. In order to ensure your aquatic plants receive all the carbon dioxide they need, you will ultimately need to invest in a specialist CO2 kit. Our buying guide explains the main features to look out for when selecting a suitable CO2 kit for your aquarium.

Aquarium CO2 Kits Explained

Along with UV light, all aquatic plants require carbon dioxide in order to thrive and function. Although plants only need a certain amount of exposure to UV light in any given day, they will need a constant supply of carbon dioxide in order to carry out photosynthesis. Aquatic plants use C02, along with water from their surrounding environment, to produce oxygen, as well as the natural sugars they utilise in order to grow and remain alive. In natural environments, plants simply pull carbon dioxide from their surroundings. In a closed ecosystem, such as an aquarium, they have minimal access to carbon dioxide.

An aquarium CO2 kit serves as an injector system, delivering carbon dioxide directly to an aquarium environment. If your tank is only used to house fish species, aquatic animals or coral specimens, you probably won’t need to make use of a CO2 kit. However, planted aquariums will almost certainly benefit from one. If your planted aquarium only receives minimal light exposure, a CO2 injector system will help provide plant specimens with the raw ingredients they need in order to grow and thrive. However, even in this scenario, a CO2 kit is not essential.

However, larger tanks will almost certainly require a CO2 injector kit. This is especially true if your plants are receiving a considerable amount of light. The more light a plant receives, the faster they can grow. The larger your plants grow, the more carbon dioxide they will require. Fish waste and the breakdown of other organic matter is unlikely to provide your plants with the required levels of CO2, so you’ll need to supplement naturally occurring levels with carbon dioxide from an external source.

Key Components of an Aquarium CO2 System

An aquarium CO2 system is made up of a few key elements. A carbon dioxide bottle is the most obvious and largest individual element. These bottles come in various sizes, with larger bottles containing more carbon dioxide. Some systems make use of reusable bottles that can be refilled from an external CO2 supply, while micro systems utilise CO2 cartridges that need to be replaced over time. If you purchase a system with a reusable bottle, make sure it is made from high-quality stainless steel that is resistant to corrosion, especially if it will be exposed to saltwater.

Another important part of a CO2 system is something called the solenoid. The solenoid is crucial for automated delivery of carbon dioxide. When combined with a timer, a solenoid will ensure that no more carbon dioxide than required is injected into your setup. If you are away from home for long periods and want a system that can be left unchecked for stretches of time, your CO2 system will definitely need a solenoid.

A regulator is another key element of an aquarium CO2 system. Most regulators will include a display gauge that will provide you with an indicator of how much gas is being delivered into your system. A gauge will also give you time to to react to any unexpected pressure changes that might be an indicator of a bigger problem.

Closely related to the regulator is the diffuser. A diffuser is what injects carbon dioxide into the aquarium environment itself. Most diffusers are fashioned from porous material, such as ceramic. This porous material ensures that carbon dioxide is delivered into your tank in the form of a mist, rather than a more concentrated form. This misting effect also ensures carbon dioxide is dispersed more evenly into your aquarium.

The best aquarium CO2 kits will also include something called a bubble counter. These counters will keep track of the amount of bubbles that are created per second. They are a handy tool for determining whether or not you need to rethink the pressure settings of your CO2 system. A carbon dioxide drop checker is another valuable feature to have. These checkers will provide you with a clear indicator of CO2 levels in your aquarium.

Product Reviews – The Best Aquarium CO2 Kits

Need a first-rate CO2 kit for a new aquarium setup? Below are some of the very best aquarium CO2 kits currently available for you to think about.

Fzone 2.5L Aquarium CO2 Generator System Carbon Dioxide Reactor Kit with Regulator and Needle Valve for Aquarium Plants Tanks

This FZONE C02 generator system has everything you need to ensure your aquarium plants thrive. This complete kit includes a 2.5-litre CO2 bottle made from high-grade stainless steel, along with a precision needle valve, a regulator and a user-friendly bubble counter that can be easily adjusted. The high-quality build of the CO2 bottle is particularly impressive, with the stainless steel housing around 25-percent thicker than what other products. This means it will be able to sustain far higher pressures than standard bottles. The safety valve is also on hand to ensure pressures never reach dangerously high levels.

If you need to maintain very precise levels of carbon dioxide in your aquarium setup, the inclusion of a needle valve and bubble counter will be very welcome. The needle valve makes it easy to finely tune CO2 levels, with the bubble counter making it effortless to monitor the level of carbon dioxide delivered to your aquarium water. These components are also designed to ensure that water can not flow back into the tank, preventing corrosion from causing you any issues. You can also optimise this CO2 kit by combining it with a timer, taking pretty much all the manual effort out of maintaining healthy carbon dioxide levels in your aquarium.


Fluval Mini Pressurized CO2 Kit, CO2 Supplement for Planted Aquariums, 20 grams, A7540

If you’re only dealing with a smaller aquarium, this mini CO2 kit from Fluval should be more than fit for purpose. This mini pressurised kit contains all the key components you will need to maintain healthy CO2 levels in a modest aquarium, with the system suitable for use with tanks with capacities up to 15 gallons.

A very reliable regulator valve means you can enjoy maximum control over CO2 output, while the ceramic diffuser ensures that carbon dioxide is easily dissolved into your tank water. A study mounting bracket is also included, allowing you to mount the CO2 cartridge directly to the side of your aquarium. If you’re worried about a CO2 system taking up too much space, this compact solution is an ideal option.

This kit has all the key ingredients you’ll need to ensure optimal CO2 levels. IN addition to a regulator valve, you’ll find a disposable CO2 cartridge and mounting bracket included. You’ll also find a hose and internal diffuser thrown in for good measure. Although this kit is fairly affordable, you will of course need to replace the CO2 cartridge on occasion. However, considering that this kit is intended for use with smaller aquariums, the ongoing cost of these cartridges will be minimal.


The Little Green Change DIY CO2 Aquarium Plant System Kit – Generator Aquarium Moss Plant D201 Tube Valve Guage Bottle Cap with Needle Valve Pressure Gauge for Aquarium Water Plant Tank

This CO2 kit from The Little Green Change is a good option for the more experienced aquarist who doesn’t mind putting in a little work to furnish their tanks with a first-rate CO2 system. If your aquarium is being used to house aquatic plants, a CO2 generator is an essential part of any setup. This kit is incredibly easy to use, with all the core elements you’ll need included. The kit comes with a reliable pressure gauge and display so you can keep an eye on CO2 levels, as well as a user-friendly gas adjuster. Pressure relief controls also make it easy to carry out precise adjustments.

The overall build quality of this CO2 kit is exceptional. The plastic housing prevents water from causing any damage to the essential components, while the secure locking features of the pipe mean that everything will hold in place once connected. The components that attach directly to your CO2 supply are made from high-grade metal, ensuring a tight and reliable seal to prevent any unwanted leaks.

The great thing about this kit is that it provides the more experienced user with a low-cost alternative to other systems. In fact, you can make use of an empty carbonated bottle to create a first-rate CO2 generator system. The trimmer valve also makes it plugging and unplugging your system incredibly easy. With precision fittings throughout, you’ll have no trouble creating a bespoke CO2 kit at home.


CO2 Generator System Carbon Dioxide Reactor Kit with Auto Valve and Diffuser for Plants Aquarium

If you’re looking for a professional-level CO2 generator system for your aquarium, this complete kit has all the main components you’ll need. The stainless steel CO2 bottle provides you with a sealed store for your carbon dioxide, meaning you won’t have to compromise with an unreliable plastic bottle. The stainless steel construction also means you can reuse the bottle for a long time, provided you keep an eye on corrosion and rust.

This kit also comes with a solenoid valve that can be combined with a timer, allowing you to deliver CO2 to your aquarium at the same time you are exposing your aquatic plants to UV light. This feature should prove particularly appealing to those with less experience in keeping aquatic plants.

The stainless steel bottle also comes with a reliable safety valve that will automatically open and release excess air should pressure levels become dangerously high. All the accessories you’ll need to put together a first-rate CO2 generator system are included here. Along with the bottle, you’ll find a pressure reducing valve, a pressure gauge, a tertiary filter, a safety vale, bubble device, solenoid valve and more. In fact, the only thing you’ll need to invest in to get started is reactant. All the individual components can be readily replaced should they encounter any wear and tear, saving you the expense of having to purchase a complete kit in the future.


Decdeal Aquarium DIY CO2 Generator System Kit CO2 Generator System with Solenoid Valve Bubble Counter Check Bubble Diffuser Carbon Dioxide Reactor Kit for Plants Aquarium

If you’re happy to spend a bit more on a CO2 generator system, this complete it from Decdeal is worth investing in. This kit is made from some very robust materials. Aluminium alloy construction means that the individual components are both durable and incredibly reliable. All connecting caps and pipes are leak-proof and will not suffer from warping and distortion after being exposed to water and high pressure levels. The professional-level pressure gauge also means you can keep an eye on pressure levels at all times. Although the kit looks complex at first glance, this system is fairly easy to use and provides you with a convenient way to produce CO2 with simple chemical reactions.

The solenoid valve makes it easy to switch your generator on and off. It can also be combined with a timer if you’re looking to take some of the effort out of maintaining your aquatic plants. However, you will need to purchase a timer separately. The safety features of this kit will also appeal to those looking for peace of mind. The safety valve will automatically release when pressure levels hit high enough levels. This valve can also be manually released should you notice any issues with your CO2 generator setup. A bubble diffuser is also included, allowing you to tailor bubble output so your plants can more readily absorb carbon dioxide and photosynthesise.


Anself CO2 Generator System Kit with Pressure Guage Safe Vavle Air Flow Adjuster for Aquarium

This CO2 generator system from Anself may look quite basic, but it has all you need to ensure your aquariums are constantly provided a reliable CO2 to source to promote natural photosynthesis. Unlike other kits in this list, this CO2 system comes almost fully assembled, allowing you to install it and start putting it to work almost immediately. The construction of this kit is very impressive, with sealed hosing and a leak-proof build ensuring optimal operation. A quality pressure gauge is also included, allowing you to keep an eye on high pressure levels. This should provide you with plenty of advance warning that there may be an issue that needs resolving.

This CO2 generator also allows for manual and automatic decompression. This not only gives you more options when it comes to maintaining and generating CO2 levels, but also makes it a particularly safe option. The airflow adjustment is also particularly reliable, with the metal connectors providing you with enhanced precision that plastic alternatives would struggle to match. If you’re looking for something affordable and reliable, this Anself CO2 generator kit is a great buy. However, it does lack some of the frills and refined controls of more expensive systems on the market.


Rhinox Nano CO2 Diffuser – Keeps Aquarium Plants Healthy with CO2 Injection – 3-Minutes to Setup – Works Best with Pressurized CO2 Tank – for Tank Size Under 20 Gallon

If you’re looking to generate CO2 in a smaller tank, this compact diffuser from Rhinox is a good option. This CO2 diffuser doesn’t match up to more elaborate kits intended for sue with larger aquariums, but if it’s a nano tank you’re dealing with, it should prove sufficiently effective to promote high levels of CO2 in aquarium water. This glass diffuser boasts a ceramic bubble diffuser that ensures bubbles rise slowly, while the cylindrical profile prevents high flow rates. Both of these features will benefit the needs of a smaller tank.

The transparent glass housing and compact design also make this Rhinox diffuser a good option for smaller tanks, with the stripped-back design ensuring you won’t have to sacrifice too much swimming space and growing room for your aquarium occupants. With fewer individual parts, this diffuser is very easy to install. The suction cup means you can attach it directly to the siding of your aquarium, while the universal connectors mean you can attach it to a variety of pressurised tanks and bottles. If you’re looking for a low-cost and low-maintenance CO2 solution, this affordable diffuser is well worth a second look.


The Verdict

If you have never used an aquarium CO2 kit before, carefully consider your options before parting with your cash. Small tanks and nano aquariums will usually be fine with a micro CO2 kit that includes replaceable cartridges, while larger tanks will require a more advanced setup. If you have no experience with putting together a CO2 system, make sure you invest in a complete kit with all the essential elements included. DIY carbon dioxide systems can be more affordable and provide you with some flexibility when it comes to delivering CO2 to a larger tank, but the margin for error is high.

As CO2 systems are made up of many individual parts, you should also invest in a kit that can be replenished with replacement components down the line. If the connectors, washers or CO2 hosing are not standard sizes, you will find it difficult to source replacement parts in the future. The general build quality of the individual components will also give you an idea of how long your CO2 system will perform for. Opt for kits with high-grade hosing, titanium connectors and stainless steel bottles and tanks if you want something that will last for years.

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