How to remove rust stains effectively.

I have been searching for the most effective mean to remove these stubborn rust stains.

I tried bleach detergent, vinegar. However none of them work. Several months later, I decide to give harpic a try.

Sprinkle affected area with some water, then pour powder harpic onto those rust stains. Leave them on for 15-30mins or more. Now you can see some stains been removed even before you brush them.

Gently brush remaining rust stains with a brush.

YESSSS...now it's back to original condition. 

My best rust stains remover : Harpic and a brush.