The Difference Between Granular Activated Carbon and Activated Carbon Block Water Filters
Activated carbon filters are frequently used as a complimentary filter for UV and reverse osmosis water filters. When it comes to choosing an activated carbon filter for these type of systems, you generally have two choices: granular activated carbon (GAC) or carbon block. Although both GAC and carbon block filters are both made from carbon that has been ground into small particulate matter, this is basically where the similarities end.
Carbon block filters have a much larger surface area, which allows them to filter out a much larger quantity of water while also being much more affective at filtering out particles, heavy metals and other contaminants. Now this isn’t to say that granular activated carbon filters are necessarily a bad choice, but it does mean that you need to be fully aware of the differences between these two types of filters in order to make a more informed decision. For this reason, we will now present a quick overview of both granular activated carbon and carbon block filters to make it easier for you to decide which is a better fit for your needs.
Granular Activated Carbon vs Activated Carbon Block Filters
Granular activated carbon filters are made using carbon that has been ground up and is held together loosely inside a cartridge or other container. On the other hand, carbon block filters are made by grinding activated carbon into a fine powder. This powder is then mixed with a food-grade binder, and the resulting mixture is then heated up and compressed into a solid block. Although both types of filters use ground carbon, the carbon found in block filters is usually ground into a much finer powder. In fact, the carbon particles in a block filter are usually 5 to 20 times smaller than the particles used in GAC filters.
The fact that carbon block filters are much more tightly packed than GAC filters means that the blocks filter out far more contaminants. Whereas some contaminants may be able to escape the loose carbon found in GAC filters, the compact nature of carbon block filters means that even the smallest particles and contaminants cannot pass through the filter. In addition, the compact nature of carbon block filters means that it takes water much longer to pass through the filter. This lower flowrate further increases the effectiveness of carbon block filters and contributes to much higher purification rates than when using a GAC filter.
The tradeoff for this level of purification is the low flow rate. The looser nature of GAC filters means that they provide a much higher flowrate, which essentially means that you can purify much more water in less time albeit less effectively. However, some GAC filters are able to achieve higher purification rates by slowing down the flowrate and thus increasing the amount of time that the water is in contact with the carbon. Although they may not provide the same level of purification as carbon block filters, granular activated carbon filters do have the advantage of lasting much longer.
Many water purification systems actually take advantage of both carbon block and GAC filters in different stages of the purification process. This shows that granular activated carbon filters do have their own uses, even if they don’t provide the same level of purification as the carbon block filters. Nonetheless, if you are forced to choose between the two, it comes down to what is most important to you: a higher flowrate or better purification.