cmills,
As you might know the Power Powder plus will raise both the CH, CL, and salt levels of your pool. I believe each bag contains 1 lb of product. That 1 lb of 73% cal-hypo will raise your FC by 2.7, your CH by 1.9 and your salt by 2.8.
With a CYA of 30 you will need to add 4x 1 lb...