I am going to try my hand at RO water and brewing salts. My next brew is calling for 7 gallons of water, 3 for the mash and 4 for sparging. Do I add all the brewing salts, including 5.2, for 7 gallons or do I add what is needed for 3 gallons and then add the salts when I sparge? I would think the later, because with 5.2 being used the ph would be off. Any help would be appreciated.