How do you remove hard water drop stains from (shower) glass?

Question

I wanted to apply Rain-X to the inside of glass walls in the shower to minimize upkeep and prevent further water stains. But if possible, I would like to get the glass really clean first. The previous owner did very little upkeep and the glass is covered with water drop stains.

I already tried Windex and lemon juice with little results.

I'll post a picture if necessary to show the type of stains.

Answer 1

CLR is best for removing buildup from calcium, lime, and rust. Just use it with care (well ventilated, and probably don't want it on your skin).

Answer 2

If you don't want to use chemicals, the Mr. Clean Magic Erasers seem to do a good job at removing these types of stains. I don't have any affiliation with the product, just a satisfied customer.

They are abrasive, so test on a small area first.