Not sure if this is the correct place for this question so I apologize in advance if it's not.
I have flagstone coping that has little black dots that look like mold. I tried to use bleach solution and SS brush but they would not budge.
Any idea what they are and how to get rid of them.
I have flagstone coping that has little black dots that look like mold. I tried to use bleach solution and SS brush but they would not budge.
Any idea what they are and how to get rid of them.