How to Choose an Activated Carbon Filter

What is Activated Carbon?

Activated Carbon is just stuff made out of carbon molecules, from materials like coconut or peat, which is ‘activated’ by heating it to high temperatures inside a special kiln. This causes it to develop an extremely elaborate network of pores and thus dramatically increases its surface area.

One gram of activated carbon has a surface area roughly equal to the size of a football field.

Activated Carbon Filters

PureZ Carbon Filter

Activated carbon block or cartridge filters are made by mixing carbon and speciality chemical binders together and compressing them at high pressure.

These blocks can filter out chlorine, taste, odor, sediment, turbidity, iron, lead, bacteria, and many other contaminants from water, depending upon the type and quality of the filter you use.

Here are 5 pro tips when choosing or replacing your activated carbon filter:


Make Sure The Source Of The Activated Carbon Is Coconut.

The main reason being, the coconut-based activated carbon, mainly has micro pores which are about the same size as the contaminant molecules in water. Thus it is very effective in trapping these contaminants. The pore size of coal and wood-based activated carbon is much bigger and thus they don’t perform as effectively when it comes to water purification.

Ash content: Another factor to take into consideration is ash content. In coal and wood-based activated carbon the ash content can be between 10 – 15 % while in coconut filters it will be between 3 – 5 %.

This means coconut-based filters are much healthier.

Advantages of coconut-based activated carbon

Check The Block Externally

Look for cracks, which can be seen as thin lines as shown in the picture. Also, look for excessive carbon dust outside the filter. Good quality filters don’t release dust excessively. A little bit of carbon dust is normal.

Also, you want to make sure the block is not to brittle. As for any stress test documentation.

Low quality coal filter blocks


Understand The Performance Metrics Of The Block

If you are buying a standard CTO (Chlorine, taste and odor) block, which is the most common type of activated carbon filter cartridge, there are just two performance metrics you need to understand: Capacity (longevity) and  Chlorine Reduction %. This data is usually represented in a graph such as the one in the figure.

It basically tells you how long (in liters or gallons) the block will keep removing chlorine, or the any other contaminant (bacteria in the case of antibacterial blocks) at an acceptable rate, 98 % in this example. After this you need to replace the filter.


Insider Tip: Ask for the Iodine Value of the Block

The iodine value or iv is what the manufacturers use to express the adsorption performance of the activated carbon. The higher the iv, the better your block will perform.

High performance carbon blocks have an iv of more than 1000.

Check with your supplier to make sure you are getting the very best.

Check For Quality Certification

The market is flooded with blocks of substandard quality and performance that might look physically appealing on the outside, but might not deliver on performance and longevity.

One way to make sure is to make sure is to look for reputed quality certifications like NSF, ANSI and WQA. These certifications are issued after regular quality inspections and elaborate product testing and are often a reliable way to separate quality products from the rest.