I have some staining on my plaster and I'm trying to figure out the best way to deal with it. There are two types. The first is a light brown on the steps and a patch on the bottom. To me it looks like it’s just dirty and I thought a brush and vacuum would clean that up. However, when I tried brushing these areas pretty hard, it had no effect at all. The other stain appears to be rust under the light fixture. Again, I tried brushing and it had no effect.
Remedies I have read include: rubbing the stains with vitamin C, rubbing stains with triclor pucks, SLAMing the pool and no drain acid wash.
Is there a preferred methodology on when to apply these treatments? Is there something else I should try?