Why you should use a CO2 scrubber for your aquarium

Aquarists use CO2 scrubbers in freshwater, and saltwater aquariums contain a protein skimmer to help control pH levels. So, if you have issues with elevated pH levels in your saltwater (or freshwater) aquarium, using a CO2 scrubber will help you maintain healthy levels.

Are you struggling to keep your pH level stable? For people looking to support growth and metabolic health in aquariums, controlling pH levels using a CO2 scrubber is one of the most reliable and straightforward ways. 

Hobbyists can install a CO2 scrubber on saltwater and freshwater aquariums as long as they have a protein skimmer. 

Most CO2 scrubbers function the same, removing CO2 from the air. Air with CO2 travels into the CO2 scrubber. The polluted air reaches an ion exchange resin, attracting any CO2 molecules present and isolating them from other gasses. 

Why Are CO2 Scrubbers Used In Aquariums?

Depending on where you live, ambient CO2 can vary, sometimes resulting in excess CO2 in the surrounding air. Even with optimum alkalinity levels, carbon dioxide (CO2) in the atmosphere is likely the number one cause of chronically low ph in the home aquarium.

Excess CO2 in the surrounding air transfers into the tank via natural gas exchange. This reaction creates carbonic acid when the ph level begins to drop; experiencing chronically low ph in aquariums causes many issues, such as calcification (bleaching) of corals and causing stress in fish, often resulting in death. 

Keeping your windows and doors open is not practical if you live in a colder climate. Therefore a CO2 scrubber makes the perfect addition to your aquarium set-up.

Evidence proves aquarists using a CO2 scrubber achieve faster growth and experience fewer ph swings.

How do CO2 scrubbers work?

An aquarium scrubber can be used on just about any aquarium, but they are challenging to maintain.

CO2 scrubbers connect to the air intake of your protein skimmer to introduce ambient air into your aquarium by bringing CO2 into contact with the media inside the scrubber, which absorbs and strips CO2 from the air and raises the pH inside your aquarium. 

Another issue many aquarium hobbyists face is algae outbreaks. If this rings a bell with you, we have good news! You can use a CO2 scrubber for your aquarium to reduce algae naturally. The scrubber will remove the CO2 algae required to grow; without CO2, algae cannot photosynthesize and spread in your aquarium.

Learn more about algae in the aquarium in this ARTICLE.

Considerations When Using A CO2 Scrubber For An Aquarium

In the aquarium trade, CO2 scrubbers are becoming more popular. However, consider a few things before using one in your home aquarium...

Carbon dioxide removal media Drying out

The most common issue with Carbon dioxide removal media is when it dries out. When the media inside the scrubber dries out, it cannot neutralize CO2, so always protect the media

Aquarium hobbyists protect the media from drying out by adding one tablespoon of water at the bottom of the reactor to keep the airflow humid enough before it hits the CO2 media, prolonging the media’s life. 

However, when we added water to the reactor, it was quickly depleted, resulting in your preferred co2 absorbent media drying out. This process works if you are okay with adding new water to the reactor every couple of days. 

CO2 scrubber

Protein Skimmer Intake

It would help if you also considered the protein skimmer intake (usually, litres per hour). The greater capacity of intake of your protein skimmer, the more air enters the CO2 media at a given time. Therefore, the CO2 concentration that enters the CO2 scrubber dramatically affects how long the scrubber can function.

A protein skimmer with a larger intake will also have a larger media capacity to store your preferred co2 absorbent media.

Air exchange with the room

If your aquarium is exposed often to elevated CO2 levels, the pH of the tank water will be lower.

Do You Need A CO2 Scrubber?

Not everyone will benefit from a CO2 scrubber. For example, if elevated CO2 levels are not the issue in your home or office, then a CO2 scrubber will not help you reduce the pH level in your aquarium water. Instead, perform an open window test and use a CO2 sensor to measure the amount of CO2 in the room. Using a Drop Checker, you can also measure the level of CO2 in the aquarium water.

Meet our bestseller! The NEW CO2 Drop Checker Kit - CO2 Concentration Monitoring Set


A CO2 scrubber also may not work if running a massive aquarium with a poor protein skimmer. 

Anyone considering using this method should have a basic understanding of how to use co2 in aquarium settings beforehand. CO2 is a pressurised gas and must be handled with care. Aquascapers familiar with injecting Carbon dioxide (Check out our range of CO2 injecting kits here) to achieve faster growth will be aware of the need to handle co2 canisters such as fire extinguishers or paintball canisters. Similar measures should be put in place for CO2 Scrubbers.

The Pro-SE Series Complete Aquarium CO2 System with in-tank Flux_ Diffuser


CO2 scrubber

How does the CO2 scrubber work?

Connecting the air intake of skimmers and other equipment to this innovative device allows it to absorb excess carbon dioxide from the atmosphere, utilizing special media that quickly strips away any harmful environmental pollutants. In doing so, these intelligent devices can raise pH levels in your aquatic domain — keeping those fish happy and healthy!


Using a CO2 scrubber in your aquarium will help raise and maintain a stable pH level needed to improve the health and growth rates of your tank’s residents.