How do operators of large commercial pools monitor water quality?

Factual Questions
1

Was at the wave pool in the waterpark section of the local amusment amusement part the other night and the lifeguards started whistling and motioning for everyone to leave. The staff told us it was a “water quality issue”. I didn’t see them do anything obvious to the water in the pool. About an hour later we were allowed back in.

Some friends of ours growing up had a pool in their backyard, and every now and then they’d dunk some test strips in, then based on that dump some chemicals of this or that in. So I was wondering how places like this do it now. Maybe sensors to monitor in real time the exact pH, chlorine levels, etc and blare out an alarm in the back room if they go out of range? Maybe some sort of automatic system to add chemicals based on sensor data to try to keep it in tolerance?

2

I work at a regional water park. At our park, one of the maintenance guys just circulates the park from the time he shows up at work to the time he leaves. He takes samples from a spot, checks it with the test chemicals, writes down something on his clipboard, then moves on to the next spot. Think he radios in to his supervisor if something is out of whack, but I don’t know.

3

Could have been a Baby Ruth ‘diaper’ malfunction.
Any chance it was lightning next town over?

4

The wizard behind the curtain adds the chemicals. They wait til the pump runs a complete cycle or two. Swimmers in.

Chemistry. Chlorine (no telling what else)water, swishing and time.