Black Spot Removal for Fibreglass Pools - Sodium Metabisulphite
You'll find these black spots on fibreglass pools typically on older pools where the shell has deteriorated over time and the cobolt has begun leeching out of the shell.
Directions for use:
Apply around the waterline with the pump off. Leave for 4 hours, then go back to the normal pump cycle.
This will remove the black spots visible as a result of osmosis.
You may need to repeat the treatment every 6 months or year (when ever the black spots reappear)
This product is an irritant when inhaled. Do not apply on a windy day. Avoid skin contact, especially when wet.
Contact Poisons Information if swallowed. Give plenty of water and do not induce vomiting.