Larry, muriatic on light colored brick with a mask test a spot. If the other corners are painted do not use muriatic on that area. You have the right stuff for the painted area. Muriatic has worked well for me on light brick.
Superior does have more experience than me and he probably knows the best recommendaion or others with many post. I just know what has worked for me and it might not be the best way. After coming back from RT in Alabama i will be more sure of my answere.