So I have black spots that wont go away. I have shocked and they get a little better, but then come back. I have been told I may need to resurface pool $$$$
You will need to scrub the spots to basically break them open so that they can be destroyed by the shock or algae treatment. This is probably black algae which can be difficult to treat, but not impossible. Apply some black algae treatment directly to your brush before scrubbing any stubborn algae spots.