1-3 ppm is the sweet spot for pool chlorine.

Between 1 and 3 parts per million of free chlorine. That’s it.

Lower than 1 ppm and you’re not killing bacteria fast enough. Higher than 3 ppm and your eyes will burn, your swimsuit might fade, and you’re just wasting chemicals. Most pool test kits measure free chlorine, so use that number. Total chlorine should be close to free chlorine—if not, you’ve got chloramines, which means shock the pool.

pH matters too, but you asked about chlorine. Keep pH between 7.4 and 7.6 and the chlorine works better. If your pool gets heavy use, hot weather, or algae problems, you can temporarily run up to 5 ppm, but that’s maintenance mode, not daily life.

Stick to 1-3 and you’re fine.