+ Dose your pool in the evening with bleach to take levels 15 ppm or higher -- 1/2 - 3/4 gallon of bleach should do it.

+ Brush your pool thoroughly the following AM.

+ Continue to dose with bleach in the PM to 15+ ppm, for 3 days after there's no green anywhere. (A gallon of 8.25% bleach will add ~20 ppm to your pool.)