Do you see the grunge on my plate? It is from the high iron content in the water, my bathtub looks just like it. I have been trying to get it off for about as long as we've lived here, but nothing was working. I found this Miracle Eraser under the sink the other day and decided to try it. Wow, it worked great! Can you see the difference when I clean one half? And see the goo on the eraser? Ewwww! Now to do the rest of set!