Leave hard-water spots too long and they etch the glass for good

When mineral-rich water dries on a window, it leaves behind the calcium and magnesium it was carrying. At first that's just a surface deposit — a chalky spot you can still clean off. But leave it sitting, especially in the Florida sun, and the minerals begin to chemically bond with the silica in the glass itself.

Once that happens, it's no longer a stain on top of the glass — it's etching in the glass, and no amount of scrubbing brings the clarity back. The window looks permanently cloudy or foggy. At that point the only options are professional glass polishing, which has limits, or replacing the pane. That's why sprinkler overspray hitting your windows every morning is worth fixing early.