I have a 10,000 gallon fiberglass, salt water pool with tile at the waterline. I don’t have any issues in the pool, just stubborn algae in the silicone that holds the tiles. I’ve tried scrapping is with a razor, spraying chlorine, chlorine tablets. Nothing works. In the first couple years I had my pool I kept the cover on a lot not understanding that I should not have been doing that and I think this is when the problem started. What can I do?! I am losing my mind. Shocking doesn’t help because the water isn’t that high.