Stain in Shallow end

[Nobody]

Good morning
I have a tan to greenish stain in the play area approxx 500 sq ft it does not reach into the deep end at all
the shallow end does get shade earlie afternoon , all my numbers are right on they did get off month back but are now looking great
after reading issues on stains in the forum i got some vitamin c tablets rubed it cam clean right away my question is how do i treat the larger area
i have tried brushing but will not do much how would i handle this
Thanks
Nobody

 

[pooldv]

That means the stain is metal. More here, Pool School - Metals in the Water and Metal Stains. There is a link to an ascorbic acid treatment also.