It is determined that the Ca++ is the contaminant ion for a mud system. In the same field, anhydrite existence is detected from previous log data. The calcium concentration of the mud was indicated as 750 mg/L. Decreasing the calcium concentration to 15 mg/L is advised. As drilling fluid engineer, state which chemical you can use to provide this concentration decrease and calculate the amount of it. (Your calculation should be based on all possible scenarios for low pH and high PH environment.) (Note that the total volume of the mud system is 2500 bbl.)