3000 ppm sodium chloride salt is 0.4 ounces weight of salt per gallon which is about 2 teaspoons per gallon.
50 ppm Borates is 0.059 ounces weight per gallon or 1/3rd teaspoon per gallon of 20 Mule Team Borax plus 0.038 ounces weight of dry acid (about 1/6th teaspoons) to get to neutral pH. For boric acid it's 0.038 ounces weight per gallon or 1/4th teaspoon per gallon.
So If i did this right, I have 2,800 gallons and then I multiply that by 0.4 = 1,120oz and then divide by 16oz I would add 70lb of salt, right?