Calcium chloride is usually used in place of Gypsum when sulfates are not desired. Calcium chloride will adjust your mash pH down. 1 gram in 1 gallon changes the salt levels by 72 ppm calcium, 127.5 ppm chloride and adds 180 ppm to the hardness.
Water: A Comprehensive Guide for Brewers
Lactic Acid (4 oz)
Phosphoric Acid (4 oz) - 10% Solution
Anvil Small Scale