APLOS Pumped/Non-Pumped Filter 1-2-3 APLOS 5-Stage Reverse Osmosis Filter is a compact DIY solution designed to improve the quality of your drinking water right under the sink. It features two sediment filters decreasing in tolerance, with a Granualar Activated Carbon filter. This product is only a replacement cartridge filter for the APLOS filter /R.O. system (Pumped/Non-Pumped) and does not include the filter housing.  It is recommended that the stage 1-2-3 Filters are replaced every 6-months. Stage 1: Uses a 5-micron sediment cotton cartridge that is designed to remove particles and impurities from water. These cartridges are typically made from cotton, which is wound around a core to create a dense filter medium.  The primary function of this is to act as a pre-filter, removing larger particles before the water undergoes further purification processes via the 0.5 micron carbon block. Stage 2: A granular Activated Carbon filter (GAC filter). Stage 3: A 1 Micron sediment filter,