Guide to CO2 equipment needed for planted tank

Injecting carbon dioxide into the aquarium looks complicated at first glance. And yes, this is not the easiest part of the aquarium hobby. Hence many hobbyists stay on the safe low tech site, thinking about the fish' safety. However, using this gas can completely change the planted aquarium with no harm to fish or other inhabitants. Understanding and choosing the right CO2 system is essential to provide your fauna and flora with a safe and healthy environment. By providing CO2 for plants aquarium can look completely different.

Aquascape by Chris Oddy

Aquascape by Chris Oddy

Benefits of injecting carbon dioxide into the planted aquarium

Before we start discussing what is essential for a well-performing CO2 system, mentioning the advantages of using CO2 is very important.

What we all remember from primary school is that plants require light energy and CO2 to produce their own food and produce oxygen for the surrounding breathing creatures. The same process called photosynthesis takes place in the aquarium. However, CO2 dissolves thousands of times slower in water than in air. Therefore delivering this gas to the closed environment is much harder than in nature. The amount of oxygen produced by aquarium plants without additional CO2 support is usually not enough to fulfill the needs of the aquarium inhabitants. Therefore having CO2 in planted aquarium gives the ecosystem a chance to achieve balance and thrive!

If you'll ever get a question about What does CO2 do for plants the answer is simple! It helps aquatic plants to make their own food and create a balance between livestock, nutrients, and light!

Ok let's move to the CO2 aquarium guide!

In this part, you will see all the required equipment to create a well-functioning CO2 system fitting your current low tech setup.

CO2 regulator

This is probably the most important part of the CO2 system which is responsible for the safety of your fish and keeping the stable pressure (not always but this matter will be explained along with diffusers). This device allows you to set the working pressure and adjust the bubble count with a needle valve. And here you need to be extra careful, especially when you have sensitive shrimp or very expensive species of fish. While setting the bubble count, it's essential to do it patiently and make adjustments after a few hours for the pH to drop. This will be visible in the drop checker (which will be also discussed later in the article).

CO2Art Pro Elite CO2 regulator

Meet the star of CO2 injection world- PRO ELITE DUAL STAGE CO2 REGULATOR- SHOP NOW!

While choosing the regulator, firstly you need to pay attention to the construction. Always choose the second stage design as it prevents end-tank-dump and actually this factor mostly makes your fish safe. End-tank-dump is when the CO2 canister finishes and the remaining gas escapes from the cylinder suddenly, which usually ends up killing all the livestock.

Another thing you need to take into consideration is what CO2 cylinder are you going to use. You can choose from a wide range of CO2 bottles: fire extinguishers, paintball bottles, Sodastream, and so on... Be aware that different types of bottles have different connection threads therefore sometimes using an additional adapter is required. This guide to cylinder connections may be helpful while making the choice LINK. If you decide on the typical refillable bottle, make sure the regulator has the correct threading (CGA320 for North America).

It's good to think about the CO2 regulator as an investment. This device is responsible for the entire CO2 system, therefore it's not worth buying the cheap stuff which is usually a long-term investment. Remember that the CO2 system works under very high pressure therefore durability and quality of the used materials are crucial.

Bubble counter

After connecting the regulator to the CO2 cylinder (and optionally adapter), the next one on the CO2 line is the bubble counter. The bubble counter is a visible indicator of the CO2 being injected into the aquarium water and should always cooperate with a drop checker. As mentioned before, any adjustments should be made after several hours when we can be sure that the CO2 was dissolved in the entire aquarium. And here it's worth paying attention to whether the bubble counter has a check valve or not. The last thing we want is the water entering the regulator and damaging the solenoid valve.

Drop checker

This is a total must-have while running CO2 injection. The drop checker is simply a glass vessel where we put a specially pre-mixed reagent that changes the color depending on the water pH. Carbon dioxide is strongly correlated with pH - the more CO2 we have, the lower the pH is. So if there is too much CO2 in the aquarium, the reagent changes its color to yellow, if too less- it's bluish. The goal is to achieve a deep green color which means that there is a balance between the CO2 concentration and lighting.

drop checker kit

Get to know 7 things you should know about drop checkers in our great article explaining this matter in detail LINK.


You may think of how actually is carbon dioxide injected into the aquarium. Actually, there are two general options:

In-tank CO2 injection

The diffuser is put inside the aquarium near the filter outlet. In-tank diffusers are available in various shapes and sizes, made of acrylic, plastic, steel, or glass. The aesthetic point of view is quite important here. The smaller and looking more natural, the better. After all, we want to show our aquatic plants and fish, not the equipment :)

Flux Bazooka Diffuser

Flux_Bazooka CO2 Diffuser - SHOP NOW!

Inline CO2 injection

The diffuser is placed on the external filter's hose and connected with the CO2-resistant tubing to the regulator. A great advantage of this solution is simply less gear inside the planted aquarium. This type of diffusion is recommended especially for larger aquariums. While choosing the Inline diffuser, always check the hose size. Different canister filter manufacturers have different standards for hosing therefore this sometimes needs some tinkering. From our experience, picking the incorrect Inline size is the most common mistake among CO2Art Aquascaping Community.

Inline diffuser CO2 Art

Get to know our bestseller among the diffusers- Inline Diffuser made with the Fine Mist Technology- SHOP NOW!

For an efficient and well-functioning CO2 system, maintenance of the diffuser is very very important! Without regular cleaning, the ceramic membrane (the heart of the diffuser) will become clogged very fast and won't allow gas to pass through it. It's recommended to clean the diffuser at least once every 2 weeks according to this instruction LINK. A very convenient way of keeping the diffuser clean is having a replacement membrane LINK used during the cleaning of the original one which doesn't rush the whole process.

CO2 resistant tubing

Nothing would be possible without CO2-resistant tubing! This type of tubing is made of materials that can stand high pressure. Avoid silicone tubing that becomes brittle and often causes leaks in the CO2 system. Maybe that's only an accessory but it really makes the equipment work as it should.


Apart from the above mentioned must-have products, there are things making the aquarium work better or look better. Newbies are often confused about the purpose of using some accessories in the planted aquariums. Therefore we'd like to say some words about each one.

Check valve

This tricky device is nothing else but a spring with a bit of plastic. Check valve permits gas to flow in one direction only, preventing water back flow and damaging the expensive regulator and solenoid valve. If you're not planning to use a bubble counter on the regulator, using the check valve is very important.


This accessory is mostly for hobbyists having a rimless aquarium (or with a very small rim). Its purpose is to provide nice tubing alignment when using the in-tank diffuser. Just put it on the aquarium edge and connect tubing to both sides of the u-bend.

Suction cups

This is a great alternative for hobbyists having a non-rimless tank. Putting 4 suction cups on each side of aquarium glass will help you to hold the tubing and not spoil the view thanks to their transparent coloration.

Inline bubble counter

This solution LINK is perfect if the bubble counter can't be mounted directly on the regulator due to lack of space. Many scapers use this device to have the bubble count under control all the time in visible place (which is not a closed cabinet :D ).


Another accessory that is a must have for the pressurized CO2 injection. It's a ring (nylon or rubber) that has to be placed between the regulator and CO2 cylinder/special adapter. This needs to be replaced each time you exchange the bottle.

Are you still asking yourself: Do I need CO2 for planted tank?

The answer is definitely yes! The CO2 system is a great thing you can give to your aquarium plants and fish. This gas completely changes the game and is a key to run a successful planted aquarium.

Below you can see the photo of Jordan Stirrat- our very talented CO2Artist who runs all his. aquariums with CO2Art gear!

aquascape by Jordan Stirrat

Still not sure what to choose?

Our support team is always ready to advise the CO2 equipment for planted aquariums! Just send an e-mail to and our experienced team will help you to pick the right gear! Among CO2Art CO2 systems for planted tanks you will find the most reliable and durable gear on the market. Join thousands of satisfied clients and get your own CO2 regulator for planted aquarium just now! Let the small bubbles into your tank and enrich the water column with so valuable carbon dioxide!