5th Stage filter for the 5 stage purification system. This is the mineral filter (option 2) which helps to add back minerals to the purified water prior to dispensing Option 1 - carbon filter (WLP6) for final finishing of water prior to dispensing Option 2 - mineral and carbon filter (WLP13) helps add back minerals to the purified water prior to dispensing Option 3 - Granular Activated Carbon (GAC) and alkaline filter (WLP12) finishes the purified water and changes the pH value from acidic (the pH of purified water is normally 6.5 depending upon the pH of the supply water) to alkaline with a pH of approximately 8.5 depending upon the pH of the supply water. 6th Stage Use WLP11 so that the GAC and alkaline filter is fitted externally and use the mineral filter (WLP13) as the 5th stage. Alternatively the purified water can be passed through the hydrogen generator to produce the perfect pH and ORP values for a detoxifying water normally only sold as an expensive bottled water.