When the pool was built I was told by pool company I’d need my coping tile sealed so it wouldn’t stain. They recommended a guy. 11 months after the pool was complete I had the coping sealed. Contacted the guy a few days later bc it was a thick sticky mess. Like Vaseline all over the coping. He came out and said he used a lot that didn’t absorb and power washed it off. It obviously ran down the waterline tile. Now every time it rains my white tile turns black. He came out again and used a pumice stone to clean the tile. It’s still turns black every time it rains. You can feel the wax coating on the tile. I know it was the sealing bc I never had this issue until it was sealed. Any chemical I can use to remove it or other suggestions?