Your hair turns green from the presence of hard metals (copper, iron, and manganese) in the pool water not by the chlorine. Try using lemon juice or vinegar to rinse hair after swimming. To prevent, put conditioner in wet hair and then swim.
Wash your hair immediately afterwards with a shampoo that takes chlorine out. There was a brand I used to use when I went swimming in high school because it did the same to my blonde hair. I just don't remember the name but it's out there.
before u go swimming, use a color protector it can be any but i prefer loreal, then after wash your hair with Paul Michelle chlorine solution, it gets rid of all the chlorine in ur hair but it keeps the color safe. I personally did that for 2 months when i died my hair bleach blond for the summer. It worked great and my hair looked beautiful for 2 months!!! i hope this works!!!