Brown stain

Could leaves cause brown stains on the white fiberglass/plactic parts of my inground vinyl pool? Stairs, skimmers etc.. I get alot of leaves in the pool over the winter.
The tannins in leaves makes sense.
I remember having this problem a few years back. It eventually went away. Magic eraser would take it off.
Any thoughts?

There can be more than one cause of staining, iron being a biggie for red/brown stains. I'm not the expert on those stains, but i would think a leaf-based stain would quickly succumb to high doses of chlorine and brushing.