Question: – What makes a good carbon block cartridge?

Answer:

Perhaps the two most important considerations would be pore size and chlorine capacity. The smaller the pore size, the greater protection the carbon block offers you through your Whole House unit or your RO membrane. But remember the smaller the pore size the more impact the carbon block filter will have on your gpm flow (gallons per minute). Carbon block cartridges with a pore size of 5 or 10 microns are the most common in the industry. Carbon blocks with smaller pore sizes will remove additional particles but are generally not necessary if the carbon block filters are being used as pre-filters for a RO system. As for chlorine capacity, most replacement filters have a 6,000 to 8,000 gallon (and much greater in large filters) chlorine removal rating. Most original equipment manufacturers will install carbon filters with a 2,000 to 4,000 gallon chlorine removal rating. Because your sediment cartridge should be in line ahead of the carbon block, the primary purpose of the carbon cartridge (the work horse of filters) is to remove VOCs – volatile organic compounds, and specifically we really want to remove chlorine.