Before we talk about Activated Carbon in this blog, it is better to know, that the Carbon Filter ( CTO & GAC ) is a series of sediment filters and able to treat water perfectly.

Activated carbon can eliminate chlorine in the water. The process can be regarded as Cl2. The reaction between water and carbon initiates the formation of Cl-, H+, and CO2.

collection of activated carbon filter

By having a direct chemical reaction with the carbon, oxidizing elements in water are eliminated. Instead of adhering to the carbon particle in this instance, chlorine chemically combines with the carbon to create carbon dioxide.

As a result, chlorine removal via carbon filters is limitless. Unlike with organic elimination, chlorine does not become saturated in the carbon bed.

What is a GAC filter?

What is GAC filter

Granule-activated carbon is made from raw organic materials, such as coconut shells or coal, which are high in carbon. The activated carbon removes certain chemicals from the water passing through a GAC filter by trapping the chemical in the GAC.

However, other chemicals, like iron and nitrate, are not attracted to the carbon and therefore are not effectively removed.

Granule-activated carbon filters are made using carbon that has been ground up and is held together loosely inside a cartridge or other container. And the looser nature of GAC filters means that they provide a much higher flow rate, which essentially means that you can purify much more water in less time with less effectively.

What is a CTO filter?

What is a CTO filter

The carbon block filter compresses loose carbon blocks together to form a filter. In the carbon block filter, one pound of compressed activated carbon (the amount in a standard 10-inch filter cartridge) has a surface area equivalent to 160 acres of farm, making it one of the most absorbent materials known to man.

There are a variety of raw materials used to make carbon block filters. Some of the most common sources of carbon are bituminous coal, wood, and nutshell.

Carbon filters remove contaminants through adsorption. Adsorption means that contaminants are attracted to the surface of the activated carbon and held to it, much the same way a magnet attracts and holds iron filings.

Granule Activated Carbon Filter Element vs Activated Carbon Block Filter Element


The carbon used to make granule-activated carbon filters has been mashed up and is loosely held together inside a cartridge or another container. Instead, activated carbon is ground into a fine powder to create carbon block filters. After combining this powder with a food-safe binder, the mixture is heated up and squeezed to form a solid block.

Filtration Accuracy

Although both the CTO and GAC filters use ground carbon, the CTO filter element’s carbon is typically processed into a considerably finer powder. In contrast to the particles used in GAC filters, the carbon particles in a block filter are typically five to twenty times smaller.

Dirty-holding Capacity

Generally, CTO filters can filter more contaminants than GAC filters, due to their more compact structures.

Flow Rate

The looser nature of GAC filters means that they provide a much higher flow rate, which essentially means that you can purify much more water in less time.

CTO filter is full of fine holes, so its ability of decolorization is excellent, but it is easy to lead to a plug problem. However, strong adsorption of GAC can perform perfectly in the same situation.

How to pick the best one for your CTO or GAC?

How to pick the best one for your CTO or GAC

When compared to a GAC at the same flow rate, the CTO’s smaller particle size and uniform pore structure offer a higher level of efficiency in a smaller housing.

Because of this, GAC is frequently employed as a technique of treatment for aesthetic impurities (removal of taste, odor and color). CTO goes beyond the aesthetic improvement of water by reducing particulates, microscopic cysts, lead, volatile organic chemicals (VOCs), and other contaminants.



CTO and GAC filters are both effective Activated Carbon filters, which have great filtration performance. They have their own strengths in different aspects.

By comparing their different characteristics, it is wise to choose the right activated carbon cartridge for yourself by combining your real usage needs. Sometimes, a combination of CTO and GAC filter cartridges can achieve the best results.

Brother Filtration has been deeply involved in the filtration industry, manufactures all kinds of filter products, and offers various filtration solutions.

We also produce high-quality CTO and GAC filter cartridges. If you still don’t know how to choose an Activated Carbon filter, please feel free to contact [email protected], and our technicians can help you solve your problems.

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