topless,

Would you mind letting me know exactly what your chlorine level was (if you know it) when you saw the algae go away? Was your CYA still at 150 or did you drain and refill some of your pool water before the algae went away? I'm trying to determine what level of chlorine is truly needed to get rid of algae and a very high CYA case such as yours is a good one to help make that assessment.

Ben's table says to shock with 25 ppm of chlorine so I'm wondering if that's the level you believe you attained. Even if you didn't measure the result, you probably calculated how much chlorine to add to get to a certain level so was it 25 ppm that you were shooting for?

Thanks,
Richard