Replacement filter package for this system is Amazon item B071GJL7KJ
All Ports are 1" NPT Inlet / Outlets <> Complete Well Water Filtration System with Quartz Sleeves, UV Bulbs, Ballasts and Standard Size 4.5 x 20" Big Blue Filters (1" Ports)
1st Stage: 5 Micron Sediment Filter. For particles such as sand, dirt, silt, and rust. To remove these particles it allows a better performance for the following Carbon Block filter.
2nd Stage: 5 Micron Carbon Block Filter. Removes chlorine, bad taste and odor, organic solvents and organic chemicals that contribute to bad taste and odor.
3rd Stage: Powerful 110W 24 GPM Ultra Violet Light Sterilizer is good to treat harmful Bacteria., E Coli, Viruses Fungi, Algae most microorganisms including cryptosporidium and giardia, and many other contaminants.