I'm closing my pool now for winter but have metal stains in pool from old pipes in heater. I painted the gunite pool two years ago. I have stains by the return in the floor and its almost creating a film over the paint to make it not look as bright. I have drained my water level to close and I'm wondering the best way to take care of this going forward.

Is it to simply drain and acid wash pool? This will not affect my paint right? With water level down I can rub walls with hand and remove the film. I pool brush does not work for this.

Vit. C does remove the stain, I tried tablets yesterday. I understand that doesn't get it out of the water though. Should I just wait till next year at opening to try and fix?

Any thoughts or concerns?

Can I post a photo some how?