Hello, I have a 20x40 inground pool. I use pristine blue as my maintenance. Use liquid chlorine to shock. Water is balanced. I was opening it up, water was clearing up, I put some A+ stain remover in to make liner shine, like I have before. And 30 min later the whole pool was brown. Never happened in 17 yrs I’ve had it. City water, no metals other than what’s in the blue. I can put a chlorine tablet on stain and it goes away, but only to return!!!! Help. Do I shock the Crud out of it and keep chlorine high for about a week? Any suggestions will be great. I thank you very much!