I don't know about the test for sodium tetraborate, I'll leave that to someone who knows about it, but your statement that "we will be ading 45 pounds of Mule Team, along with muratic acid" really scares me.....you don't need to add 45 pounds of ANYTHING to a 15K gallon pool! 20 Mule Team Borax raises pH, and muriatic acid lowers it. You don't need to add both--if you do, you're wasting money and chems. All you need to do for pH is raise it with Borax or lower it with muriatic acid to keep it between 7.2-7.8--but you need to add slowly, so as not to overshoot your target number.

Janet