How to Use Liquid Carbon in Your Planted Aquarium

Live aquarium plants require carbon dioxide (CO2) to photosynthesise and generate energy. Hobbyists use CO2 gas to increase plant growth speed in high-tech planted tanks. But what if you don’t want to deal with expensive CO2 injection systems? 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. Continue reading for more information about liquid CO2 and how you can best use it to grow your aquarium.

What is Liquid Carbon?

Many aquarium companies offer liquid carbon as part of their plant fertilizer collections. Liquid CO is also known as liquid carbon dioxide and liquid CO. It may be sold under the brand names Seachem Flourish Excel and API CO2 Booster in the United States. Almost all of these products contain glutaraldehyde or similar chemicals, which is known to reduce algae growth within a planted 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. It is much easier and quicker to get CO2 directly from the air than it is to grow aquatic plants with their leaves out in water. 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. Initial studies showed that liquid carbon has a lower level of CO2 than the recommended dosage. A normal aquarium with adequate surface agitation and gas exchange using a filter or air stone will produce approximately 3-5ppm CO2 in its water. This is higher than the amount of liquid carbon.

While liquid carbon is often used to replace pressurized CO2 gases, we believe it’s more useful in inhibiting the growth of algae.

What’s the difference between activated and liquid carbon? Although their names might sound similar, activated carbon is used to chemically filter water. Liquid carbon is used in plant tanks. Activated Carbon is a filter media that captures impurities such as medications, tannins, or other chemicals from water.

Is liquid carbon dangerous to humans? Treat glutaraldehyde as carefully as you would treat bleach. Do not swallow, inhale, or touch the liquid. Rinse it off if you have it on your skin. If you get it in your eyes or mouth, rinse thoroughly for 15 minutes. For USA customers, reference the poison.org website. For Canadian customers, reference dpic.org.

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 CO2 in Planted Aquariums

Easy Carbon is an algicide that we use to control algae growth in planted aquariums. The algae will return to your tank regardless of how much Easy Carbon you use. Easy Carbon contains 1.5% glutaraldehyde and 0.5% citric acid, and a 16 oz (500 ml) bottle treats 5,000 gallons of water.

How often should I use liquid carbon? Dosing with Easy Carbon is very simple, since the bottle already comes with a pump head. For low light aquariums, use 1 ml (1 ml), of Easy Carbon every other day. Use the same dosage on a daily basis for medium to high light aquariums. Start with a lower dose and increase the amount after you have evaluated its effects for at least two weeks.

You can also use liquid carbon to treat stubborn algae such as 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 the filter back on. You should begin to see signs of algae discoloration or weakening in as little as 4-7 days. You can try a second spot treatment the following week if the first one is unsuccessful. Do not overdose the tank beyond the recommended amount of liquid carbon or else the plants in the aquarium may be adversely affected.

Which plants can be sensitive to liquid carbon? Anacharis and vallisneria have a reputation for melting when exposed to 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 does my tank get cloudy water after using liquid CO2? Because liquid carbon is killing off algae, little particles of dead algae may detach and float into the water column. Regular water changes and improved mechanical and chemical filtration can help remove the particles from the water.

Why isn’t Easy Carbon getting rid of algae? If algae is not going away despite regular usage of Easy Carbon, then most likely the tank is too unbalanced in terms of lighting and/or nutrients. 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.

Find out more about plant nutrients in our article on selecting the best aquarium fertilizer. Enjoy your garden and the outdoors every day.