THIS WORKS!!
Hard water stains are the worst. The buildup we had in our bathtub was out of hand. And I tried for hours, scrubbing and using different products and I made progress but it was slow and I was so worn out. So I ordered Brite & Clean. Just amazing!  Yes I still scrubbed and used some elbow grease but I had decreased my efforts 80%. I loved it so much that I ordered a second bottle to have on hand!  It also cleaned up ALL hard water stains off my granite countertop around the sink. I had given up hope of ever getting rid of that  I highly recommend Brite & Clean.
Rating: 5 stars