How to use Liquid Carbon in Your Planted Aquarium

How to Use Liquid Carbon in Your Planted Aquarium

Live aquarium plants require carbon dioxide (CO2) to photosynthesise and generate energy. Hobbyists often use pressurized CO2 gas in high tech planted tanks to boost the speed of plant growth, but what if you don’t want to mess with an expensive CO2 injection system? Some companies claim liquid carbon dioxide is an effective substitute for CO2 gases, while others argue that it is a chemical treatment to get rid of algae. Keep reading as we discuss what is liquid carbon and how to best use it in your planted aquarium.

What is Liquid Carbon?

As part of their plant fertiliser collection, many aquarium companies offer liquid co2 (also known as liquid CO2 or liquid carbon dioxide). You may see it sold in the United States under brand names like Seachem Flourish Excel, API CO2 Booster, and our own Aquarium Co-Op Easy Carbon. These products almost all contain glutaraldehyde, or similar chemicals. This is known to decrease the growth of algae in an aquarium. The growth of aquatic plants is often faster and healthier when there is less algae competing with nutrients, light, carbon dioxide and other chemicals.

Does liquid CO2 replace pressurized CO2 gas? While liquid carbon is often marketed as a source of carbon, many planted tank experts agree that it is a poor replacement for CO2 gas. Many aquatic plants prefer to grow without their leaves in water. This is because it is faster and easier to access CO2 gas from the air. Therefore, people set up high tech tanks to help their underwater plants by injecting more CO2 gas into the water at concentrations ranging from 10-30 ppm. Some initial studies have analyzed how much CO2 is released from recommended doses of liquid carbon, and the numbers were significantly lower than pressurized CO2. In fact, an aquarium that has good surface agitation, gas exchange with an air stone, or filter, results in about 3-5 ppm of CO2 in the water. This is much higher than what liquid carbon seems to provide.

Although liquid carbon is commonly sold to replace pressurized CO2 gas (which we prefer), it can be more effective as an inhibitor for algae growth.

What is the distinction between liquid carbon or activated? Both are used in filtration systems. Activated Carbon is a filter media that captures impurities such as medications, tannins, or other chemicals from water.

Is liquid Carbon dangerous to people? Use glutaraldehyde the same way you would bleach. The liquid should not be swallowed, inhaled, or touched. If you get it on your skin, rinse it off. If you get it in your eyes or mouth, rinse thoroughly for 15 minutes. For USA customers, reference the website. For Canadian customers, reference

Is liquid CO2 harmful to fish? While we can’t speak for other manufacturers, Easy Carbon is safe for aquarium fish, shrimp, and snails when used as directed.

How to Use Liquid Carbon dioxide in Planted Aquariums

Easy Carbon is an algicide that we use to control algae growth in planted aquariums. No matter how much Easy Carbon is added, the algae will continue to grow in the tank unless it is properly balanced. Easy Carbon is made up of 1.5% glutaraldehyde (500ml) and 0.5% citric acids. It can be used to treat 5,000 gallons.

How frequently should I use liquid carbon. Easy Carbon’s pump head makes it easy to douse the bottles. Low light aquariums will need to use one pump of Easy Carbon (1 ml) every other day. For medium-high light aquariums, use the same dose on a daily basis. Start with a lower dose and increase the amount after you have evaluated its effects for at least two weeks.

Liquid carbon can also be used for spot treatment on stubborn algae like black beard algae. Turn off the filter and circulation pumps, and use a pipette to spray a few leaves underwater with Easy Carbon as a test. After a few minutes, you can turn on the filter again. If the algae has been affected, you should see signs of weakening and discoloration in 4-7 days. If spot treatment is successful you can target a few additional leaves for the next week. Don’t give your aquarium more liquid carbon than it needs. If you do, the plants could be affected.

Which plants are sensitive to liquid carbon? Certain plants, like anacharis and vallisneria, are notorious for melting away in the presence of liquid carbon. If you have sensitive plants like these, consider dosing at half the recommended amount.

While liquid carbon is safe for fish and invertebrates, certain plants like vallisneria may be more sensitive to it.

Why do my tanks get cloudy? Liquid carbon kills algae. This means that small particles of algae may float to the surface of your water. Water filtration that is both mechanically and chemically improved can remove these particles.

Why isn’t Easy Carbon killing algae? The most likely reason is that your tank is too inefficient in terms of nutrients and lighting. You can reduce your daily lighting by using a power outlet timer for 2-hour increments. Wait at least two weeks before you make any major changes.

You may find that your aquarium has low levels of nitrate around 0-5ppm. This could indicate that your plants are not getting enough nutrients. Follow the instructions to apply Easy Green all in one fertilizer. If your aquarium always has above 40 ppm nitrate, you can reduce excess nutrients from the water by doing more frequent water changes, feeding less fish food, or moving some fish out of the tank.

You can find more information about fertilizers for aquarium plants in our article How to Choose the Right Aquarium Plant Fertilizer. Best of luck with your planted tank, and enjoy nature daily.