All - thanks for taking the time to read this. I recently noticed a few small black spots that would not brush off when cleaning. They are about a quarter size and only in one corner of the pool. I know black algae can grow from not maintaining a balanced pH level but is this what it is...black mold? The water is currently balanced. The water and pebble tech in all other corners of the pool is clear and spotless. Any advice on how to remove and prevent would be greatly appreciated. Thank you!