Permanent stains or fixable?

[tclary47]

Pictures don’t do it justice on how dark they are but we had algae that was eradicated and left behind these stains in plaster. No metals in the pool as I’ve tested for that.

Is vitamin C tablets best course of action next to try and remove the stains?

TIA

Balanced pool. Everything within range on the test kit.

 

[Texas Splash]

Is vitamin C tablets best course of action next to try and remove the stains?

Not for organic. Try sprinkling some cal-hypo granules on the area and brush it around every few seconds. You could also try rubbing a chlorine puck and move it slowly around, but they are sort of small for large areas. Other than that, increase the FC level a bit higher (between normal and SLAM level) and continue with brushing daily.