Roof Runoff Concrete

Good Morning,. Just looking for a little help here. This concrete brick building has had dirty roof run off hitting the concrete for God know how long. We went at it yesterday with 6% SH and soap and it had zero effect. Well almost zero effect,. Any place that wasn’t stained cleaned up and so did the stucco like surface around the trim so now the stain sticks out more. Can anybody recommend a “home Depot” like product I could pick up today that might get the stain… Living in Canada makes it tough to get good chemicals quickly…
Any information would be welcomed

Search the forum, there are several Canadians on here that have talked about buying chemicals/where to get them. I can’t remember what threads contained that information.

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You have three ways to go:
Stronger SH
Degreaser
Acid

I’d try them in that order.

And try a little pressure if you haven’t.

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