Jack's Magic Power Blue Scale Off is a great at removing calcium carbonate and efflorescence. Designed specially to remove scaling from about your water line. Scale Off will remove 2-4 mils of scale per application.
Spray apply PBSO to dry tile, glass block, vinyl or stucco using a trigger spray bottle. Use full strength, adjust the spray nozzle to stream stream (do not mist or aerosolize). Spray directly onto the scale and watch this amazing product go to work immediately dissolving the scale. Spray and brush, repeat until scale is gone, then rinse.
At first sign of reappearance of white scale or efflorescence, spray apply PBSO again, for easy removal and maintenance.