Wheel Of Fountain

This is an outdoor fountain with 7 or so years of accumulation of minerals. I'm scraping with a blade razor blade scraper singles. Have tried CLR but it does not even come close to cutting it. Would acid, but try to find that you eat the glazed tiles. wire brush will not work, and a wire wheel in a mill hand would probably scratch the glaze. Anyone suggestions?

Try "Lime Away" ... Put it on and let it sit for 15 minutes. Sound like a tough job.
Good luck