Rusty type stain on my steps-( pic inside)

[freddyttt]

Have this rusty type stain upon opening of pool. tried the magic spong which got 75% off but some remains-. any ideas?? on what it is and how to remove it??

thanks-


[IMG][/IMG]

[Watermom]

Could it be an iron stain? Do you fill from a well?

[freddyttt]

Thanks no I do not fill from a well. however iron was my thought. anyway to remove it...