large black/brown stains on deep end floor

[krista]

with low, very low ph I added ph+ and alk powder. Due to corrosion in my heater, the next morning there was a lot of turquoise copper throughout pool and large blackish stains where ph was thrown. Stains will not come off. Treated as a mineral with sequestering agent, no luck. Did the vitamin c thing, no luck. Now treating as an algea, no luck. Any suggestions???????????? Vinyl liner in pool. Thanks