Reverse Osmosis product water is more acidic due to it's purity. By the time the water is processed through the various stages, after the reverse osmosis stage, minerals etc has been removed. To replenish necessary minerals, an alkaline filter is recommended. The alkaline filter, reverse osmosis product water tends to be acidic due to the purity of the water. All minerals have been stripped from the water. To buffer the water to a more natural alkaline state, and to add essential minerals back i.e. calcium, magnesium, potassium and sodium. We highly recommend the alkaline filter. This filter will increase the alkalinity without over correcting.This alkaline antioxidant filter provides abundant Active Hydrogen and also increases reduction power by increasing pH, making small water cluster and providing beneficial minerals. Negative ORP potential, which is produced with ionized alkaline water, severely retards the aging process. By counteracting oxidation damage to our cells. It does this by hunting down free radicals in our system and neutralizing them. Negative ORP is a very powerful anti-oxidant. and is found naturally in orange juice, glacial runoff and deep underground uncontaminated aquifer or spring water.