If the water is green, it can eat up chlorine very, very quickly. With a CYA of 50, you need to get your chlorine up to 15 ppm and hold it there, and it will clear quicker. I'm with Watermom on the chems--it would be better to leave off the algaecide and not add anything else but chlorine to your pool. The algaecide can deplete your chlorine almost as fast as the algae can!

Janet