Got everything balanced

pH = 7.5
CYA = 60

6 gallons of household bleach (6%) and the chlorine went to 20 PPM yesterday evening. This morning the chlorine was back down to 3 PPM, so I backwashed and added 2 more gallons of bleach. I plan to add another 2 gallons this evening.

How long will I need to hold the chlorine level to 20 PPM?

THE WATER WAS NOT GREEN, BUT CLOUDY/BLUE THIS MORNING!