We had a concrete patio installed two summers ago. We stained and sealed it with Quikrete. Apparently the stain and sealer were not compatible and the whole thing started chipping. We tried power washing it and finally renting a concrete buffer with carbide tips. It did remove a lot of the stain/sealer but there is still some left in the grooves from the brush strokes of when the concrete was poured and textured. I was told to try some chemical treatments like muriatic acid. Does anyone have suggestions?