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Do you really need Co2 for planted aquarium aquascape

As you probably remember from your science classes, CO² for planted aquarium aquascape is one of the most important gases present on this planet. CO² is present everywhere where there is life, from forests to underwater environments.

When knowing such things, it’s normal to be asking if CO² is needed in a planted tank. To answer this question, we will first review what CO² exactly brings to plants. I will then give you guidelines on when you should use CO² and when you don’t really need to use it. Finally,

I will tell you how to set up a CO² supply for your planted tank so you can get started quickly if you need it!

Why is CO2 important in a planted tank?

If you ask if CO² is important to someone who isn’t very informed on the subject, he might tell you that CO² is a very dangerous gas that causes ozone layer damage and global warming.

Frankly, with everything bad, we read and hear about CO² everywhere. It wouldn’t be shocking. Still, you have to remember that before being the dangerous gas that will make the water level rise and threaten the Human race, it’s the gas responsible for all life on Earth.

As no planted life would be possible without CO² and us humans need plants to live, you can see that CO² is pretty crucial and good in moderate amounts.

The plants present in your tank are no different than those present in nature. They will require CO² to be able to achieve photosynthesis, the process by which they turn light into energy.

Without a good CO² supply, plants won’t be able to gather enough energy to grow properly. As one of the goals of Aquascaping is luxurious and mature vegetation, it will be wise to supply enough CO² to your plants.

As even if you choose what plants will grow in your tank, CO² will dictate how well and big they will grow and if they will reach their true potential.

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As you probably know, CO² is part of the three most critical things plants need to grow and live with proper lighting and good macro and micronutrient supply.

Nutrient supply is pretty straightforward as the fish in your tank will naturally supply the plants with their waste; you can, of course, use fertilizer if you suspect a deficiency.

It’s a bit more complex for CO² and lighting as they are both linked, the amount of lighting needed and usable by a plant is dependent on the amount of CO² supplied to it; therefore it’s important to try to reach a good balance between the two to have optimal growth.

Photosynthesis is used to convert the light energy into carbs that the plant can use to feed and grow, at the end of this, the plant will emit oxygen into the water as waste which can be in turn used by your fish.

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As photosynthesis is a natural process, it’s meant to occur with the light of the sun; you will, therefore, need a high enough light intensity to trigger it.

One thing to be aware of is that CO² to light imbalance will cause the development and spread of algae in the tank. CO² is always present in your tank, no matter if you add it or not. Fish naturally produce CO² (like humans) when breathing.

However, even if the natural CO² level may be enough for your plants to survive, it won’t be enough for them to thrive and reach their full potential.

As you learned, plants prefer to live in a tank where there’s a good presence of CO². For the optimal growth of your plants, you should aim for 10 to 15 ppm.

Keep in mind though that while CO² is good for your plants, too much of it is harmful to your fish. Keep CO² under 30 ppm, and your fish won’t be in any danger.

A CO² deficiency will cause many problems in your planted tank. The main problem will, of course, be that your plant’s growth will be stopped. It’s crucial to solve any deficiency quickly as it will cause irreversible damage, and you’ll be better off getting a new plant.

In order to spot a CO² deficiency, observe the stems and leaves of your plants. If they appear pale or start to turn yellow, it’s most likely a sign of CO² deficiency.

If the deficiency is not taken care of quickly, it can worsen and even cause the death of the plant. But a deficiency can be even worse in some cases and trigger a chain reaction that could harm your whole tank.

When CO² is depleted, plants can start getting coated with lime. These lime deposits, when in contact with the water, will raise the pH of your tank; this will make both your plants and fish more vulnerable to diseases and can even cause death if the imbalance is too big or if you have certain fish species that require strict pH control.

When do you need CO2 in a planted tank?

We’ve explored CO²’s properties and what it does for plants, as well as the consequences of a deficiency.

You may think it’s mandatory to add CO² to your tank now, but it will depend on your goals and the type of tank you’re going for before anything else.

Low tech tank

Low tech tanks are ideal for beginners and people without much time since they require less time and money to get started and maintain.

Since low tech tanks are all about results without much human interaction, no CO² supplement is one of the benefits you will have.

However, this benefit comes at the price of a lot less lush and impressive vegetation. Low tech tanks are a lot more minimalistic and not really good for showing off.

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You shouldn’t need to add CO² yourself if you start noticing deficiencies, you can either add some or simply get rid of some plants if you don’t want to spend more time maintaining your tank.

High tech tank

If you’re aiming for great and lush landscapes, then a high tech tank is what you need! A high tech tank is all about maximum human interaction, time and money investments to get maximum results.

Even if it may be more appealing to go for this type of tank, you should still try a low tech one if you’re a beginner or if you don’t have much time.

You will most likely invest heavily in good lighting, which will require a very good CO² supply to be used effectively. Natural CO² produced by your fish won’t be enough to sustain the growth, and you will need to add some on your own.

How to add CO2

Adding CO² to planted tanks wasn’t invented yesterday, it can be traced back to as early as the ’90s. However, the practice has evolved a lot during these years. CO² injections are now common practice in the aquascaping scene; as such, you will be able to find CO² injection equipment in most aquarium shops as well as advice on how to do it on many places online.

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CO² injections mainly come in 2 types: gas and liquid. If opting for gas injections, you will have three ways to do it: using yeast, setting up a pressurized system, and using an aerosol.

You should discard aerosol if you plan on setting up a high tech tank as they are mainly used as a cheap and quick way to fix a deficiency in a small tank.

Unfortunately, yeast isn’t good as well as it’s a very random way of adding CO² to your tank, as it’s obtained by the fermentation of the yeast it’s going to provide very inconsistent results.

While DIY yeast also exists and provides better results, I would strongly advise against it. Even if it provides more consistent results at a relatively lower price, setting it up can be a real pain.

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The only thing you should use to deliver CO² to your planted tank should be a pressurized system.

They really are the easiest solution to set up and use; many systems exist, and you will find plenty of tutorials and help online to set up and use the most popular ones.

The main problem when going with pressurized systems is the price, it’s indeed the most costly way to inject CO² into your tank, but if you want to add CO² to your tank, then you were probably prepared to invest a good amount of money into your tank anyway.


In this article, you’ve learned about what CO² does for your plants and why it’s so crucial if you want lush and developed plants. Always keep in mind that plants require good lighting in order to grow properly and that the more light they use, the more CO² will be needed.