Hard Water

I have a problem developing in my 55 g freshwater community tank. I have glacial runoff well water, very hard, ph 8.8. The fish I have are fine and happy. HOWEVER I'm getting the hard mineral buildup on the sides. I need to get it scraped off without messing up the Zen.

Tank's glass, and it will barely scrape with even a putty knife. I've tried hauling city water and mixing it in, but it doesn't help.

Suggestions?

Thanks, actually, since my ph is so high, I have added 1-2 tbsp onto the scratcher and used that, while fish were in the tank. It works, I just don't kow if it's safe for the fish. I use vinegar on everything else in the house. I don''t think a couple blubs will hurt in a 55, but just checking!