Need to trouble shoot these stains. The plaster is a little scratched/chipped and where to does there are brown stains. This only occurs around these scratches. I am in the process of selling the house and want the pool to look as good as possible. Was re plastered in 2010. Water specs are usually kept normal per the pool calculator app, but I do have higher than normal calcium, but tend to keep the PH slightly acidic per previous direction that you can live with higher calcium levels in a pool.
Any ideas what to use to test what would take them off?