I recently had my pool deck installed with a stamped colored concrete border around the pool and then brushed concrete for the pool deck. So the stamped powder release they use to darken the stamped concrete has stained the perimeter of my fiberglass pool around the top of the walls (almost like a ring around the water line). Has this happened to anyone else or anyone have any ideas on how to fix this? Some sort of pool cleaner that helps or something non-abrasive that won’t affect the gel-coat, but will remove the stains? Thanks!