He probably did not put in enough chemicals to keep it balanced and sanitized. He did not add chlorine until maybe 2 weeks into the water being filled. I asked why and he said the chlorine isn’t good for the new plaster. I did not know and assumed he knew what he was talking about since he is the “professional.” He only added chlorine in the second week because the water started to look a little hazy/cloudy. It cleared up right away. He would keep the FC at the bare minimum and would sometimes drop to 0 before he would come out next and add more chlorine.
I only realized there was a problem when I was adding salt and trying to get my SWG up and running. I wasn’t producing much FC and every time I added chlorine, it would drop quickly. So, I did an OCLT last night and it failed. Although, the water was crystal clear an CC was 0.0-0.2, my FC was deminishing too quickly and my SWG wasn’t keeping up.
My guess is the 30 day start up guy doesn’t really care about your pool. He just wants to put in the bare minimum chemicals to save money and make sure the pool/water looks good. Once he is done, he is gone unless you pay him for regular maintenance. Even then, who knows how they would take care of the water?