why adding chemicals to the pool water is done instead of draining and cleaning

Question

I see a lot of videos of cleaning pools and I don’t understand why heavily dirty pools aren’t just drained instead of adding things to it. Is it cheaper? Aren’t the chemicals harmful? Is the concentration harmful?

In: Other

Answer 1

Just to clarify, I understand why people clean pools but I don’t understand some instances when it’s heavily dirty and requires a lot of chemicals. That’s why I’m asking.