Why is my pool still green even though my chlorine levels are normal?

It’s probably phosphates, not your chlorine. Phosphates from leaves, lawn fertilizer, or tap water feed algae and burn up your chlorine’s power. Check your phosphate level with a test, and if it’s high, use a phosphate remover, then shock the pool. Also check your stabilizer (CYA) and pH—high CYA locks up chlorine, and high pH cuts its effectiveness. Fix those three, and the green usually clears up in a day or two.