Based on the 'fizzy' test (bubbles when in vinegar or acid), you can probably remove those . . . but SLO-O-OWLY. If you want to remove them rapidly, you'll need to drain and acid wash. I don't recommend that, because acid washing damages the finish.

To remove them in place, you need to lower the alkalinity to 60 ppm or so, and hold it there, till the scale is gone. You'll probably loose a bit of your finish, too, but not nearly as much as you would if you acid washed. To lower your alkalinity, read this page: http://pool9.net/alk-step/