Aquarium without CO2: is it worth the effort?

You don’t want to invest in a CO2 system and you wonder: is it possible to have a planted tank without CO2? The answer is yes! But of course, this is subject to conditions if you don’t want to get into trouble…

Aquarium without CO2? Reduce the aquarium lighting!

If your tank is bathed in light, your plants get plenty of energy and grow fast. This natural reaction forms the basis of plant photosynthesis. However, plants that grow fast need a lot of nutrients and CO2. And of course, this becomes an issue if you go for a tank without CO2…

To prevent CO2 deficiency (download my e-book about the symptoms) en algae problems, you need to go the other way around: reduce the lighting so that your plants have a slower growth and a reduced need for CO2. Here is what you can do:

• Limit the light duration to 8 hours a day
• Add plenty of floating plants
• Remove any reflectors
• Use weak lighting (such as T8) or install a dimmer

It’s always a priority to limit the INTENSITY of your lights. Limiting light DURATION also helps but my experience tells that it’s a lot less effective.

Is it possible that a weak lighting causes problems to your aquarium plants?

No, normally it shouldn’t. Your plants are going to grow more slowly, but in a healthy way and without algae. In the past, tanks used to be delivered with weak lighting and aquarists were able to grow plants in them without any problems. In fact, planted tanks were less prone to algae problems than nowadays.

You do need to keep in mind, however, that not all aquarium plants enjoy a stay in a weakly lit aquarium without CO2. Some plants would rather go for strong lighting, plenty of CO2 and an abundance of plant food.

So, what are the best aquarium plants for an aquarium without CO2?

Here are a few examples of nice plants that do very well without CO2:

• Java fern
• Cryptocoryne
• Echinodorus
• Anubias
• Some types of mosses
• …

Before you buy any plants, do a web search to see how much CO2 they need.

Aquarium without CO2: for whom is it a good option?

Why would you want to go for an aquarium without a CO2 system? There can be several reasons:

• You don’t have a budget for a CO2 system
• You want as little work as possible
• You don’t like water changes
• …

If you recognize yourself above, then it’s really worth a try.

For whom is an aquarium without CO2 a BAD idea?

Unfortunately, this method is not for everyone. You really don’t want an aquarium without CO2 if:

• You want to grow special or challenging plants
• You want a nice “grass carpet” in your tank
• You want to see fast growth
• Your tank is equipped with strong lighting

In those cases, to be honest, I would advise against a tank without CO2. You would get disappointed by the plant growth or worse, you would get algae problems.

How about the water changes?

It is very well possible to do water changes in an aquarium without CO2. You can find tips about water changes in this article. For example, you can adopt a Sunday routine in which you do a 50% water change and use this time to clean your tank and do a general maintenance. Wipe the glass, clean the drop checker, prune your plants here and there…

Do you prefer to change less water, for example 25% every week? You can do that, but make sure that you have a good filtration system to process all waste. Given that a water change allows for getting rid of waste, a lighter water change needs to be compensated by a better filtration.

Is it worth investing in a CO2 system?

In my opinion, yes…

As I often say, a CO2 kit is the best investment you can make for a planted tank. Carbon dioxide (CO2) is one of the most important nutrients for your plants. So, when you add “real” CO2, you’ll notice that your plants grow much faster and better. Moreover, you will have much more choice among aquarium plants and you’ll be able to use stronger LED lighting.

So, it’s really worth considering. Hesitating on what to buy exactly? I wrote an article on how to recognize a good CO2 kit.

Conclusion

It’s possible to have an aquarium without CO2, but under certain conditions:

• You have to use weak lighting
• You are limited to easy aquarium plants

Moreover, you need to settle for a slow plant growth. But if you actually want fast-growing plants, special plants or a nice “grass carpet”, then I recommend you to invest in a good CO2 kit.