I have beautiful white draping crepe myrtles near my swimming pool. I found a couple of spots in the bottom of my pool (black mini-pebble) and thought they were bleached from shocking my pool last summer. Today I saw similar stains on concrete directly under a white crepe myrtle at a local business in town. It literally looks like the white flower melted into the concrete and it had an identical pattern and texture as the stains in my pool.

Does anybody know what I can do to get that off of my pool surface? It doesn't rub off. In fact it has a glossy texture that feels like a permanent hardened white plaster.

Any ideas would be helpful.

Thank You