Hard water residue got you down?

If you have a refrigerator with a ice/water despensor in the front you may see that there's a build-up of hard water residue in the spill tray. I don't know what causes it, but it looks terrible. We tried using CLR on the tray but that didn't work. I'm not sure what made me think of doing this but one day I mixed about 1/2 cup of white vinegar with a whole can of Coke in a tall cup and sat the spill tray in it for about 20 minutes. When I took it out and rinsed it with water it looked brand new which was nice because I was about to order a replacement part when the idea of this mixture came to me.