I had a pool a LONG time ago overseas. Chemicals were way different (fuming hydrochloric acid, solid NaOH pellets, solid chlorine granules) and downright dangerous. You wouldn't believe the close calls I had with hired help that didn't understand English nor anything about pool chemistry and the dangers of these chemicals. So I did it all myself for 4 years and I swore I'd never have a pool again but my wife helped change my mind (happy wife, happy life). Fast-forward 35 years and we love our new pool. Things are clearly way better now with all the great products. And I've learned a lot here on this site. I've been traveling extensively since we had our pool built 2 years ago so I used a pool service. They generally did a reasonable job but when I came home the chlorine level was always high (10ppm+ with less than 20 CYA). Today I finally finished the traveling and I plan to do the pool maintenance myself. I got a TF-100 kit and ran the tests. Chlorine is 20 ppm!! Everything else is normal except CYA that is less than 20. CC is also very low at 0. PH and the other tests are all normal... so I turned off the chlorinator and took the tablet out. Last time this happened it took about a week for the level to get down to normal levels. We have very little loading and a screened in pool so sunlight doesn't seem to degrade chlorine very fast. I've checked chlorine levels with test strips, oto, and the FAS/DPD. They all seem to confirm the FAS/DPD (ran it twice). So here's my question, am I missing something? Is there some reason the pool service would do this? I've questioned them about this several times over the past year about the chlorine levels but they just blew me off with "we test every time". I'm about to fire them but I just want be sure I have the brain trust here weigh in first.
All commentary/advice is much appreciated.