Best CO2 System for Planted Aquarium – (2020 Reviews 🏅)

November 24, 2019

Best CO2 System for Planted Aquarium – (2020 Reviews 🏅)

Today's post is all about CO2 systems for planted aquariums. Usually when people start out trying plants in a aquarium they want to to go without CO2 injection. There are many reasons for this including intimation factors, costs, complexity, and lack of information. The fact of the matter is if you want an eye popping prizing winning planted aquascape, a quality CO2 system and injection protocol is a necessary component. 

Today I not only want to go over what equipment you will need, but also dive into the science as to why CO2 injection and CO2 systems are such a critical factor of success when it comes to have a stellar looking and thriving planted aquarium. Knowing the science will help you understand the bigger picture, and throughout the various articles I have written that is always my goal. It's not my intention to just push products to you but rather educate you on the the reasons why we buy equipment and how it helps with our aquarium keeping journey.

As a quick disclosure, this post will include affiliate links for which I may make a small commission at no extra cost to you should you make a purchase. Now, let's get on to the topic. Let's first start with CO2 in nature.

Understanding the Role of CO2 in Nature

This actually may surprise you, but the majority of plants available for sale in our hobby are marsh plants. These plants have the ability to grow either submerged or above the water. Many of these plants would actually prefer to grow above the water! The main reason why is CO2.

You see, gas diffusion in water is 1,000s of times slower in water compared to our air above the water. This means it is much easier for plants to breath in the CO2 in our atmosphere versus taking it in completely submerged in water. It is much easier for these plants to get their CO2 needs met above the water. In fact, many of these plants in nature will seek higher ground by growing on rocks. Knowing that you can actually grow plants above water in one reason why advanced aquarists will do "dry starts" in planted tanks to establish plants and then fill with water for an easier start.

This is also a drawback if the plant matures out of the the water. Aquatic plants adapt in the water so they can work with the slower gas diffusion. Plants maturing out of the water will be thicker and heavier. In water, they will be more spread out and lighter. It is also a industry secret not known to many aquarists that aquaculture farms will actually grow their aquatic plants emerged. This is primarily to fuel rapid grow and also to save on the cost of CO2 injection. CO2 is plenty in our atmosphere, but we need to work harder to get better conditions in the water.

CO2 Levels For Aquatic Plants In The Wild 

It is a fact that most natural environments where our aquatic plants grow are evaluated in CO2. Many of our plants naturally grow in springs or river banks. These areas get flooded in CO2 as it cannot gas off leaving to extended periods of high CO2 levels. At its peak, we are taking about levels as high as 50 ppm of CO2. A non-CO2 injected aquarium will only have at most 3 ppm of CO2. That is a world's amount of difference!

Plants can obtain the CO2 that they need in other ways, but the process is very energy intensive and not as efficient. We also have to keep in mind that around 50% of our plant dry mass is carbon! An aquatic plant will use nearly 10 times more carbon than any other macro or micro nutrient in your water. 

Take a second to think about that. Many companies try to sell you on fertilizers and substrates, but the golden ticket to killer growth is CO2! This is why we really need to take CO2 injection seriously if we want to create a showstopping aquascape.

How Much Does It Cost To Setup a CO2 System For A Planted Tank?

You will need three critical parts for a proper CO2 system:

  • CO2 Regular
  • Diffusor
  • CO2 tank

On average it will cost you about $200 to setup a proper CO2 system in a 40G tank. To maintain levels, it will cost about $5 a month to refill your tank with CO2. If CO2 injection is too much for your budget, it would be best to consider aquarium plants that will thrive without CO2 injections.These will include plants like Java Fern, Pearl Weed, and Dwarf Sagittaria.

The Best CO2 Systems for Planted Aquariums

The list below are CO2 system parts for you to consider. I will weigh in with the pros and cons of each part. There aren't really complete sets available on the market...well there is one available from Fluval, but it's so undersized and the replacement CO2 cans are so expensive I can't recommended it. All of these components when put together will competently manage CO2 levels in your planted tank.

Picture Name Type Links
FZone Aquarium CO2 Regulator

FZone Aquarium CO2 Regulator

CO2 Regulator
Double Sun CO2 Regulator Double Sun CO2 Regulator CO2 Regulator
NilocG Aquatics CO2 Regulator NilocG Aquatics CO2 Regulator CO2 Regulator
NilocG Aquatics Diffusor

NilocG Aquatics Diffusor

Sera Flore CO2 Reactor Sera Flore CO2 Reactor Diffusor
Mr Aqua Turbo Diffuser Mr. Aqua Turbo Diffusor Diffusor
Coldbreak CO2 Tank Coldbreak 5lb CO2 Tank CO2 Tank


1. FZone Aquarium CO2 Regulator - Bang for the Buck CO2 Regulator

FZone CO2 Regulator Review

The FZone CO2 Regulator is a comprehensive CO2 regulator that is available at a reasonable price for aquarists. It is surprisingly high quality given it's price point. This is coming from a person who is used to seeing high quality CO2 regulators command prices over $200. This regulator also has the advantage of being DC powered, which means it will draw less electricity to operate and is easier to accommodate in the event of a power outage. This package also comes with a bubble counter - which will allow you check the flow of your CO2 using a high precision needle valve. This CO2 regulator offers the same features that you expect with higher priced regulators and FZone also offers a Triple Stage Regulator. The bubble counter also has a check value feature.

It will not fit paintball tanks standard, but the accessory to accommodate them is not that expensive. It also only offers a 1 year warranty. However, given it's features and price it's a good choice to consider.


  • Dual Gauges
  • DC Powered
  • Reasonable Price


  • Will not fit paintball tanks
  • 1 year warranty

2. Double Sun CO2 Regulator - Value Conscious AC Power Regulator

DoubleSun CO2 Regulator Review

The DoubleSun CO2 Regulator is another value conscious CO2 regulator that is AC powered. AC power will draw more electricity than a DC power device, but AC tends to be more reliable in the long-run so this one makes my list as a consideration. It offers all the same features as the F Zone regulator with slightly different aesthetics being black and gold. It is well built and good for the price. It offers the same bubble counter, needle valve, and check valve features. 

It will not fit paint ball tank and only offers a 1 year warranty.


  • Dual Gauges
  • Reasonable Price


  • 1 year warranty
  • Will not fit paintball tanks

3. NilocG Aquatics CO2 Regulator - Small But Mighty

NiloG Aquatics CO2 Regulator

The NilocG CO2 Regulator offers a good choice for those with limited space or who want to use a paintball tank instead of a standard CO2 tank.It is an all aluminum construction that is high quality. It lacks a few features of the others like a bubble counter, but it's the size that is the main selling point here. It's a better consideration than the Fluval kits for those will smaller tanks.


  • Size
  • Aluminum construction --- won't rust
  • Fits paintball tanks out of the box


  • Expensive for size
  • No bubble counter
  • No check valve

4. NilocG Aquatics Inline Atomizer - Reliable and Effective

NilocG Aquatics Inline Atomizer

When it comes to a diffusors on a CO2 system. There are three choices we have in our systems. There are standard diffusors, which are what we mostly see. They are cheap, need to be maintained often, have to be kept inside the display tank, and some are not as reliable as they should be.

This brings us to the next type of diffusion method, which is an inline atomizer. This are fitted inline with a filter like a Canister Filter and are less effected by flow inside the display tank. They produce an very fine mist, which makes the bubbles less noticeable in the tank. This Atomizer By NilocG is a great choice if you want to use one. It is a high quality atomizer that will only need to be cleaned every 2-4 months and will provide service for a lifetime. They can handle a large amount of pressure and can service larger tanks.


  • Heavy duty built
  • Works in-line with filter or pump
  • No large bubbles in tank


  • Requires higher pressure from your regulator
  • Expensive

5. Sera Flore CO2 Reactor - Eliminate CO2 Mist

Sera Flore CO2 Reactor

At the premium level of diffusion for CO2, we have CO2 reactors. These reactors capture CO2 and keeps it running in its chamber until full dissolution is achieved. This is great tool for those of us who want a bubble free, mist free display tank. They are more effective than diffusors or atomizers, but require a bit more touch to get right. You also have to purchase the correct size to handle your load.

This CO2 Reactor From Sera Flore is a great selection for a CO2 reactor. They can work externally or internally, which make them a great option for those with Aquarium Sumps.


  • Bubble and mist free CO2 dissolution
  • Most effective dissolution method
  • Well built


  • Requires higher GPH to operate correctly
  • Expensive

6. Mr. Aqua Turbo Diffuser - Easy Solution for Sumped Tanks

Mr. Aqua Turbo Diffuser

The Mr. Aqua Turbo Diffuser is a great choice for those of us with Aquarium Sumps. It's a modified powerhead that goes internally in your aquarium and works to dissolve CO2. What I like about it is that it is simple and effective. It's a separate piece of equipment, so it makes it easier to unplug and maintain instead of taking out your plumbing with an inline reactor. Cleaning is just easier and dummy proof in my mind and easier to replace if it breaks.

It is ugly to place inside your display tank, especially with that giant printed text logo. I prefer to keep everything out of the display tank for aesthetic purposes. This simple piece of equipment fits the bill.


  • Stand alone equipment
  • Easy to service and clean
  • Can work in a sump


  • Expensive for what it is
  • Looks ugly inside a tank

7. Coldbreak CO2 Tank - Cheap CO2 Tank

Cold Break CO2 Tank

The beermaking hobby has definitely made CO2 gear cheaper and easier to find. This CO2 Tank from Coldbreak is a high quality CO2 tank for a very reasonable price. It's easy to order from Amazon and is quickly delivered. Once you have one of these on hand, it's easy to exchange your CO2 tank from a local welding shop or brewery. Make sure any tank you get has hydrostatic stamps. This means they have been tested and get re-tested every 5 years.


  • Reasonable price
  • Durable and sturdy 
  • Easy and convenient to order


  • Cheaper to buy secondhand if you can find it

Additional Equipment to Consider

I have supplied a list of recommended equipment that is reasonably priced that will get you going with great success. There are other pieces of equipment you may want to consider that are theoretically optional, but recommended.

The first would be a timer. The reason for this is to save on CO2 and to properly dial in your system when your plants need it. With a timer, you will want to set your CO2 system to turn on 2 hours before your lights come on and turn off 1 hour before your lights go off. Having a timer makes this dummy proof and easy to implement. In general, most tanks will have CO2 turned on for about 8 hours per day.

You do not need a fancy timer or a controller to achieve this. A simple Mechanical Timer will do the job reliably.

The next piece of equipment would be a Drop Checker. This drop checker will monitor your CO2 levels and let you know if you are over or under dosing CO2. This particular Drop Checker works like a Seachem Ammonia Alert badge in that it is easy to read and easy to use. This is a standard on how to monitor your CO2 levels. There is a more advanced method of monitoring your pH drops when your CO2 system is off, but that to me is a more advanced topic. You can also look for warning signs from your livestock. Livestock that are in CO2 levels that are too high will show signs of stress. These signs will include lowered activity, erratic behavior, inverts like snails going above the water line, and fish moving towards areas of high flow. You want to aim for keeping your CO2 levels from 20 - 35ppm. A drop checker will turn green at 30ppm indicating that you are in the "sweet spot" of CO2 saturation.

Stainless Steel Skimmer

The final piece of equipment would be a surface skimmer. This Stainless Steel Surface Skimmer fits the bill with it's clean design and function. Surface skimmers increase gas exchange and will keep your water surface clean. The improved gas exchange from the skimmer will help optimize your CO2 levels. It's a reasonable investment to make considering that they are so invaluable to a top notch planted tank.

How To Setup A CO2 System For A Planted Tank

Setting up a CO2 System can seem like an intimating affair, but the equipment recommended here will make installation easier than you think. Once you have installed your system, you will want to aim to have your CO2 system operating at 30-40 PSI. This video by ADU Aquascaping will help visualize a standard installation of most CO2 systems you will purchase.

Going Premium - High End Options

The regulators in particular that I have outlined here are more budget friendly options. While they are good quality and will last, some planted tank keepers desire a regulator with a better warranty or may want a well-known brand name. With that being said there are two options I would recommend for those seeking a premium brand and unit. These units would be from Green Leaf Aquariums or CO2 Art. Both units offer long warranties (with Green Leaf Aquarium regulators offering a lifetime warranty and they are made in the USA).

GLA CO2 Regulator

Either option will cost over $200 for the regulator alone. Keep that in mind when shopping. A regulator is the heart of a CO2 system so it does make sense to spend extra on them if you have the budget.

FAQS About CO2 In Planted Tanks

Does CO2 Harm Fish?

It actually can if the saturation levels get too high for too long. This is why you must monitor your levels. Looks for the warning signs I mentioned earlier.

Do Planted Tanks Need CO2?

As I have mentioned earlier in the article, many of our aquarium plants in the wild are used to higher levels of CO2 then what is in a non-CO2 injected tank. As a result, many plants available in the trade will not grow to their full potential if CO2 injection is not supplied. CO2 levels at an optimum level will not only make your plants grow faster, but it will impact their coloration, health, and form. The comparisons between a non-CO2 tank and one that is injected are worlds apart. If you are serious about building a great looking aquascape, CO2 is a must consideration. It's actually more important than substrate.

Can A Low Light Plant Benefit from CO2?

Absolutely! CO2 is such a critical health component to an aquarium plant. Low Light Aquarium Plants + low powered lights + CO2 setup is actually a great way to have slower but healthy growth in your aquascape. Can't complain about less pruning :). 

Further Reading

Books are always essential when learning about the hobby. One particular book I would recommend to get in-depth knowledge from aquatic plants in our hobby is Aquarium Plants by Christel Kasselmann. It is one of the most comprehensive books you can get regarding aquatic plants and their care. 

If you want further guidance in general outside of my blog, you can check out Freshwater Aquarium for Dummies, 3rd Edition. I am the technical editor of this book and worked closely with the author. 

Closing Thoughts (Best CO2 System For Planted Tank)

I hope I have done a good job at explaining the benefits and reasons why to consider CO2 injection in your planted tanks. I also hope I have achieve my goal of presenting the best CO2 system parts for your desired setup. If you have any questions, please leave a comment below. Thank you for reading!



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