I've had a green pool ever since opening in May...one pool store sold me Staintrine. Didn't help. They said my chemicals were perfect. Today I took water sample to a different pool store. Told them my story... they said my phosphate level is 1000. Sold me commercial phosphate remover and calcium stuff. Then I started researching what phosphates do to the water and it makes sense, as we are surrounded by trees and debri got in the pool. BUT, do I really just need to shock or SLAM (??)... my CYA level is OK at 30ppm and I'm getting no chlorine level. 17.000 gallon pool, above ground.