There is little if any evidence of danger to you children swimming in 8ppm chlorine, espec with CYA=100. 8 is the MINIMUM FC you should have at that CYA level.

There is CENTURIES of evidence of the danger in swimming in improperly sanitized water. Cholera, typhoid, other water-borne diseases. Killing algae has no effect on them.

The clerk doesn't know her elbow from a turnip when it comes to pool chemicals.