{"id":295,"date":"2021-12-29T23:57:34","date_gmt":"2021-12-29T23:57:34","guid":{"rendered":"https:\/\/rootedtank.com\/?p=295"},"modified":"2021-12-29T23:57:35","modified_gmt":"2021-12-29T23:57:35","slug":"do-low-tech-aquarium-plants-need-co2","status":"publish","type":"post","link":"https:\/\/rootedtank.com\/do-low-tech-aquarium-plants-need-co2\/","title":{"rendered":"Do Low-Tech Aquarium Plants Need CO2?"},"content":{"rendered":"\n

All aquatic plants require CO2<\/sub> to photosynthesize and produce glucose. However, pressurized CO2<\/sub> systems are not required to provide adequate CO2<\/sub> to an aquarium. Small amounts of CO2<\/sub> are naturally present in water from fish and and bacteria respiration and from the atmosphere.<\/strong><\/p>\n\n\n\n

There are many factors that affect an aquarium’s CO2<\/sub> levels. In this article, we explore why CO2<\/sub> is important and how you can grow healthy aquatic plants in your low-tech aquarium<\/a>.<\/p>\n\n\n\n

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Why do low-tech plants need CO2<\/sub>?<\/h2>\n\n\n\n

Aquatic plants use carbon dioxide (CO2<\/sub>) in the process of photosynthesis to create glucose. This glucose is used as energy to help plants grow.<\/p>\n\n\n\n

CO2<\/sub> is one of a few important ingredients in maintaining healthy aquatic plant life. The other key ingredients are light and fertilization.<\/p>\n\n\n\n

Plant leaves contain organs called chloroplasts. Inside these chloroplasts are pigments called chlorophyll. Chlorophyll absorb light waves and use its energy to convert CO2<\/sub> into glucose and oxygen.<\/p>\n\n\n\n

The glucose is used as energy for the plant to grow, while the oxygen is released into the surrounding water.<\/p>\n\n\n\n

Can I grow plants without CO2<\/sub>?<\/h2>\n\n\n\n

No. Plants will not grow if they don’t have access to CO2<\/sub>. However, this does not mean you need an expensive high-tech CO2<\/sub> system to grow aquatic plants.<\/p>\n\n\n\n

The truth is that CO2<\/sub> is naturally present in pretty much all water sources. There is an abundance of CO2<\/sub> present in the atmosphere. This atmospheric CO2<\/sub> is absorbed by water as a dissolved gas.<\/p>\n\n\n\n

This means that adding plain tap water<\/a> to your tank will provide plants with some level of CO2<\/sub>.<\/p>\n\n\n\n

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Tap water contains carbon dioxide<\/figcaption><\/figure>\n\n\n\n

However, the may be factors that are limiting how much CO2<\/sub> is in your aquarium which we will dive into next.<\/p>\n\n\n\n

How do fish provide CO2<\/sub> for plants?<\/h2>\n\n\n\n

Fish, bacteria and other micro-organisms breathe in oxygen and exhale CO2<\/sub>, similar to how humans do. This acts as a secondary source of CO2<\/sub> to your aquarium as well.<\/p>\n\n\n\n

Fish and plants have a symbiotic relationship with each other. Plants convert CO2<\/sub> into glucose and oxygen. And fish breath oxygen and produce CO2<\/sub><\/a>. They each produce what the other needs.<\/p>\n\n\n\n

How much CO2<\/sub> do low-tech plants need?<\/h2>\n\n\n\n

A low-tech tank without CO2<\/sub> injection will typically have a base concentration of between 2-3ppm of CO2<\/sub>, which is adequate for growing easy and undemanding aquatic plants.<\/p>\n\n\n\n

The base concentration of CO2<\/sub> is determined by atmospheric equilibrium<\/h3>\n\n\n\n

2-3ppm CO2<\/sub> is the atmospheric equilibrium that a body of water will typically stabilize at. In other words, the balance between CO2<\/sub> in the atmosphere and CO2<\/sub> in an aquarium will naturally balance to a point of equilibrium.<\/p>\n\n\n\n

It’s useful to understand the concept of equilibrium<\/em> when thinking about CO2<\/sub> and oxygen levels in your aquarium.<\/strong><\/p>\n\n\n\n

Imagine you have a can of soda, which has CO2<\/sub> on the inside at a high pressure, and the air outside of the can at a lower pressure.<\/p>\n\n\n\n

When you crack the can open, the pressure inside releases and equalizes with the atmosphere around it. In nature, gases are always moving from a state of high pressure to low pressure<\/a> to achieve equilibrium<\/em>.<\/p>\n\n\n\n

The same is true for our aquariums.<\/p>\n\n\n\n

The concentration of oxygen and CO2<\/sub> in our aquariums are constantly trying to achieve equilibrium with the air above it.<\/p>\n\n\n\n

Aquarium water absorbs dissolved CO2<\/sub> gas from the air around it<\/h3>\n\n\n\n

The air outside of our tanks contains approximately 400ppm of CO2<\/sub>. Because the water in our tank is a liquid and the air is a gas, the equilibrium point causes the concentration of CO2<\/sub> in our tanks to be approximately 2-3ppm.<\/p>\n\n\n\n

This is before any other factors which may alter the CO2<\/sub> levels, such as fish respiration and decaying plant matter.<\/p>\n\n\n\n

High-tech tanks increase CO2<\/sub> concentrations up to 30ppm<\/h3>\n\n\n\n

High-tech tanks with pressurized CO2<\/sub> canisters are able to increase a tank’s CO2<\/sub> levels by constantly injecting CO2<\/sub> gas. This added CO2<\/sub> causes an unequal concentration of CO2<\/sub> in the aquarium compared to the air around it.<\/p>\n\n\n\n

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CO2<\/sub> drop checker in a high-tech setup<\/figcaption><\/figure>\n\n\n\n

Therefore, atmospheric equilibrium is constantly working against a CO2<\/sub> system to try and remove CO2<\/sub> from it.<\/p>\n\n\n\n

High-tech tanks may increase CO2<\/sub> levels to as high as 30ppm to achieve optimal plant growth, while not harming fish inhabitants.<\/p>\n\n\n\n

How do I increase CO2<\/sub> in my tank?<\/h2>\n\n\n\n

Remove air stones<\/h3>\n\n\n\n

You can increase an aquarium’s CO2<\/sub> concentration by removing air stones. Air stones increase the surface area where your tank water and air meet. This increases the rate at which excess CO2<\/sub> can escape your tank.<\/p>\n\n\n\n

Air stones work by creating bubbles that float to the water surface and pop. This popping creates a larger surface for which atmospheric equilibrium can occur.<\/p>\n\n\n\n

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Surface agitation increases surface area<\/figcaption><\/figure>\n\n\n\n

As you can see in the diagram above, the agitated water surface has 12 units of surface area compared to just 8 when the water is stagnant.<\/p>\n\n\n\n

Remember, atmospheric equilibrium works to achieve a balanced concentration between the water in your aquarium and the air around it. So an air stone only increases the rate at which this process can occur.<\/p>\n\n\n\n

Meaning, an air stone will only decrease your tank’s CO2<\/sub> concentration if it is already higher than the equilibrium point.<\/p>\n\n\n\n

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Aquarium air stone<\/figcaption><\/figure>\n\n\n\n

And if your tank has and equal or lesser amount of CO2<\/sub> than this equilibrium point, the air stone will not reduce the CO2<\/sub> levels any further.<\/p>\n\n\n\n

This applies to oxygen as well. Adding a bunch of air stones will not increase the oxygen levels above and beyond what is naturally possible via atmospheric equilibrium.<\/p>\n\n\n\n

Add more fish<\/h3>\n\n\n\n

The more fish you have in your tank, the more carbon dioxide they will produce via respiration. We do not recommend overstocking your aquarium, though.<\/p>\n\n\n\n

But if you have room to add a few more fish then that may be a viable method for slightly increasing your tank’s CO2<\/sub> levels.<\/p>\n\n\n\n

Decaying plants<\/h3>\n\n\n\n

Dead plant leaves and decomposing soil will produce a source of carbon<\/a> for your plants. So consider retaining this decomposing plant material instead of vacuuming it out.<\/p>\n\n\n\n

This material will also produce more ammonia, which will promote the growth of larger bacteria colonies. This will slightly increase CO2<\/sub> levels due to bacterial respiration.<\/p>\n\n\n\n

Other methods to counteract lower CO2<\/sub> levels<\/h2>\n\n\n\n

The reason you may be researching CO2<\/sub> levels is because your plants are not growing as well as you would like them to be.<\/p>\n\n\n\n

So here are a few tips for improving plant growth when you are unable to increase CO2<\/sub> levels.<\/p>\n\n\n\n

Determine whether or not CO2<\/sub> deficiency is actually the problem<\/h3>\n\n\n\n

For starters, it’s possible that your plants are not growing because of another reason entirely. For example, perhaps they’re not getting enough light or nutrients.<\/p>\n\n\n\n

Here are a few common symptoms of low CO2<\/sub>:<\/p>\n\n\n\n