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Do fish produce enough CO2 for plants? (Yes, but…)

Do fish produce enough CO2 for plants? This is the question many people have when they want to grow lush and vibrant live aquarium plants in their tank.

And in this article, I am going to answer this question so keep reading.

Do fish produce enough co2 for plants? (Yes, but...) image

So, do fish produce enough CO2 for plants?

If you are keeping low to moderate light aquarium plants in your tank then fish does produce enough CO2 for them.

But if you are highlighting to your aquarium plants then the plants likely need CO2 injection to take advantage of the light and grow faster and denser. 

If you don’t inject CO2 then the algae will take advantage of the light and grow in your aquarium.

How much CO2 is needed in a planted aquarium?

planted tank with fish

There is no one answer fit for all aquariums.

The amount of CO2 is needed for your planted tank really depends on the species of the plants you want to plant in your tank. And your goal with your planted aquarium.

If you want to keep hardy, low to moderate light aquarium plants in your tank then these plants don’t need a lot of co2.

And they can do well with the co2 produced by the fish in your tank and from the natural gas exchange that happens on the surface of the water of your tank.

On the other hand, if you want to keep demanding plants in your tank then these plants require a lot of CO2 as well as light and nutrients to grow.

For example, if you want to grow small carpet plants like Dwarf hair grass, Dwarf baby tears then these plants grow faster and healthier with additional CO2 injection.

Or you want vibrant coloration of the colored plants then usually you need to inject CO2 in the tank.

Also, if you decide to inject CO2, you’ll have to test and go through a trial and error process for determining exactly how much CO2 you need to inject in your aquarium.

Basically, you should start with 1 bubble per second of CO2 and increase the bubbles every day and until you notice the fish in your tank are stressed out or coming to the surface gasping for air.

The gasping behavior of fish suggests that you’re providing too much CO2 in your tank. And it is causing oxygen deficiency in your tank.

So, in this case, you should reduce the co2.

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Do you really need co2 for aquarium plants?

planted tank with fish

As mentioned earlier, whether you need CO2 or not is dependent on your aquarium set up.

You can create a thriving planted aquarium without CO2.

The planted tanks that are grown without injecting CO2 in the aquarium are known as low tech tanks.

Now, these tanks don’t have anything to do with the technology.

You just don’t have to add or inject CO2 and there is no CO2 injection system in place that’s why they are called low-tech tanks.

You can easily convert any fish only aquarium into a low tech planted tank.

The pearling effect that you see in high tech tanks, it is also achievable in low tech tank.

Besides, low tech planted tanks are very easy to maintain. And you don’t need a lot of technical knowledge to maintain a healthy low tech planted tank.

Also, as low-tech planted tanks don’t require a lot of equipment unlike high tech tanks they are very inexpensive to maintain.

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How to grow a planted tank without CO2 injection?

low tech planted tank with fish

Now I’ll tell you some things you’ll need and a few things that you should keep in mind to create a thriving low tech planted tank.

1. Nutrient-rich substrate

The most important thing you will need to create a thriving low tech planted aquarium is a high quality nutrient-rich substrate.

This is because using a nutrient-rich substrate increases your chances of success drastically in creating a thriving low tech tank.

You can even keep some demanding species of plant and they will do well if you have a nutrient-rich substrate in your tank.

Besides, plants root better in soil compared to sand or gravel.

Also, when you use a nutrient-rich substrate in your tank, you don’t need to dose fertilizers to your aquarium plants for a few months and even to a year.

Because the nutrients present in the nutrient-rich substrate will be sufficient for the plants and they will last for a few months to a year depending on how many plants you have in your tank.

We recommend ADA Amazonia Aqua soil.

You can check its reviews and latest price at Amazon here

2. Plant hardy, low light aquarium plants

Planting low light and hardy aquarium plants is very important if you want to create a thriving low-tech planted tank.

There are a lot of varieties of low-tech aquarium plants available that you can easily keep in your low tech tank.

A few examples are as follows:

  • Different varieties of cryptocoryne 
  • Monte Carlo
  • Christmas mass
  • Amazon sword
  • Different types of Anubias
  • Java fern
  • Water wisteria
  • Water Sprite
  • Different species of Vallisneria
  • Bucephalandra
  • Red plant like Ludwigia repens
  • Java moss
  • Dwarf sagittaria
  • Pearlweed

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3. Low to moderate lighting

In your low-tech planted tank, if you’re using fluorescent light, you should provide the light anywhere between 1-3 Watts per gallon depending on the species of plants you have in your tank.

Or if you are using LED light then the lighting should be between 15 to 50 micromoles.

It is very important not to provide highlighting in low tech planted tank because it can cause algae growth in your tank.

Here are a few low to moderate LED aquarium light recommendations

  • Finnex planted Plus- Check its reviews and latest price at Amazon here.
  • Fluval 3.0- Check its reviews and latest price at Amazon here.
  • Current satellite Pro- Check its reviews and latest price at Amazon here.

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4. Use hardscape

In low tech tank, you don’t have a luxury of a co2 injection so vibrant, dense plants but you can certainly take advantage of beautiful hardscapes to produce stunning results.

So, you should definitely take advantage of hardscape and use hardscape in your low tech tank.

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5. Use fertilizers

Plants require essential micro and macronutrients for their proper growth.

And when the plants get all the essential nutrients they grow faster and better.

Though if you use a nutrient-rich substrate, after some time, the nutrients from the nutrient rich substrate will get used up by the plants and it will get exhausted.

That’s why it is very important to dose small amounts of fertilizers to the plants in your low-tech tank at least after a few months of setting up the tank.

Also, you should be consistent with the dozing.

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6. Consistent maintenance

Now, this goes without saying.

You need to be consistent with the maintenance to create a beautiful and healthy low tech planted tank.

What I mean by maintenance is you should regularly trim the dead or decaying leaves and the leaves on which you noticed algae growth.

You should also do water changes regularly.

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When and why you should consider injecting CO2 in your planted tank

high tech planted tank with fish

Though you can create a thriving low tech planted tank, there is only so much you can do with a low tech planted tank.

Setting up a CO2 system and injecting CO2 in your tank can dramatically improve the growth speed and coloration of your planted tank.

1. Vibrant coloration

Though there are some red aquarium plants you can grow in low tech aquarium, the options are very limited.

Besides, you can’t get the vibrant, rich red coloration in a low-tech tank.

When you inject CO2 in your tank along with increased lighting and nutrients, the coloration of all the aquarium plants in your tank planted tank improves drastically.

So if you’re going after vibrant, rich coloration then you should consider injecting CO2 in your planted tank.

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2. Carpet plants

There are several carpet plants that can be grown in low tech tanks but the speed will be very slow.

When you upgrade to a high tech tank then there are a lot of options to choose from when it comes to carpet plants.

And, with CO2 injection, the carpet plants will grow very fast covering all the surface of your tank.

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3. Compact and denser growth

If you want your aquatic plants to grow compact and dense then you will need to provide additional CO2 in the tank by injecting CO2 in your aquarium.

The thing is, when the plants are not getting sufficient CO2, they try to get the CO2 from the surface of the water of the aquarium. Because that’s the part where a lot of CO2 is present as gas exchange happens near the surface of the water in your tank. 

This causes plants to grow vertically. 

But when you inject CO2 in your planted tank, there is a lot of co2 present throughout the tank.

This causes the plants to grow wider and denser which looks stunning.

Besides, the stem and the leaves of the plants grow healthy when there is a good amount of co2 present in the aquarium.

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Downsides of injecting CO2 in aquarium

Now you know the benefits of injecting CO2 in your tank, you should also know the drawbacks of injecting CO2 in your aquarium as well.

1. High cost

CO2 equipments are pretty expensive and the startup cost can get more than 250 dollars.

Besides, the gas in the CO2 cylinder will get exhausted after a few months. So you will also have to refill the tank which doesn’t cost a lot of money. But, overall, it usually costs up to 5 dollars every month.

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2. CO2 injection

When you’re dealing with high tech tank you do have to go through some trial and error and you need to have some technical knowledge about CO2 and managing gas exchange.

This can be a bit tricky, especially for beginners.

That’s why if you are a beginner then you should stay away from high tech tanks. And only upgrade to high tech tank when you have some experience with live aquarium plants.

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3. Maintenance

When you inject CO2 in your aquarium, you expect faster growth of the plants.

So you have to do the trimming and pruning of the plants more frequently.

Besides, you will also need to do water changes more frequently, especially if you are providing high lighting to the plants to keep the tank clean and free from algae.

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Conclusion

Overall, do fish produce enough CO2 for plants really depends on the setup of your aquarium.

If you are keeping hardy aquarium plants and you are providing low to moderate light to them in your aquarium then the CO2 produced by the fish in your tank will be sufficient for the plants.

On the other hand, if you are keeping delicate and demanding aquarium plants or providing highlighting to the plants in your tank then the CO2 produced by the fish in your tank most likely will not be sufficient for the plants. 

And you will need to inject CO2 in your tank or else you will notice algae growth in your tank.

I hope you found this article helpful.

If you do, please share it.

Happy aquascaping!

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