1st thank you for reading... I have a bad black algae problem in my pool, I just tried to pressure wash it, pool is drained, but it had zero effect on the algae. I have mixed a chlorine paste to wipe on the side of the walls over the black algae spots. This seems to help reduce the color but also kind of turns my plaster blue. Im not sure what to do at this point... my pool was just acid washed in March and hasnt had a problem I have seen since Ive owned the house 2.5 years ago... Im in AZ pools about 10-15,000 in ground w/sand filter
Any thoughts on what I can do?