APEC Water Ultimate series complete 6-stage high capacity filter set APEC ultimate series high flow 6-stage complete filter set is made in USA with the highest quality filtration components to provide a longer lasting filter set to protect and prolong the lifespan of your reverse osmosis system. Premium quality pre-filter cartridges lasts over 12 months while the membrane and post carbon filter last 3-5 years for fewer filter change outs and high performance impurity removal. These standard size filters are compatible with APEC Water RO-PH90. 1st stage: high-grade 10 inch high-capacity polypropylene sediment filter -removes dirt, particles, and rust. 100% pure polypropylene depth filter with exceptional dirt-holding capacity translates to longer life and fewer change-outs than existing string-wound or resin-bonded filters. 2nd and 3rd stage: premium extruded carbon block 10 inch - gets rid of unpleasant chlorine, tastes, odors, cloudiness and colors. Also removes VOCs and other common harmful synthetics from the water. 4th stage: High rejection 90 GPD TFC reverse osmosis membrane. Removes a wide variety of impurities including arsenic, chlorine, lead, fluoride, chromium, radium and more. 5th stage: advanced coconut shell refining carbon 10 inch - TCR filter removes any possible residual taste from the tank. 6th stage: 10 inch high purity ph+ calcium carbonate re-mineralization inline filters with quick connect -increases ph level of the water by adding calcium carbonate mineral back into the water.