power washer and well water stain

In one thread people say power washing can be great for poured concrete--make it look new. In another thread it ruined stamped concrete.

My problem is well water stain. Sometimes called "rust" around here. I have this stain on the sidewalk from the sprinkler system. It didn't bother me. But then someone scratched the surface a lot and now it looks horrible.

Anyone with experience removing well water stain from gray sidewalk?

One person said try CLR and power washing; another said spray on something called whiteox and then just hose it off.

I am not really interested in just trying different stuff. I want to know what works and will pay to have it done right.

I don't want to damage the concrete or make things look worse.

 

A lot will depend on the staining you have. If it's more a calcium mineral deposit on the surface or if it's mostly iron rust staining that permeates deep into the concrete will make a difference.