UPDATE:

This morning, the water was definitely MUCH LESS green and MUCH MORE milky. When I cleaned my Pentair/PacFab cartridge filter, it was a LOT easier to clean the pleats with the hose than when there was slimy green algae.

My question now is: At what ppm do I need to keep the Cl levels until the water TOTALLY clears up? 20's per Ben's best guess CYA chart? 30's per advice of Duraleigh? Something else?