My first post here. Glad I found this site. I have had an inground plaster pool for 31 years this month. I have a strange thing happening and it has me stumped. Using a test strip. I just opened the pool this week by the way. All the readings on the strip are at maximum. PH, TA, FC & Stabilizer (CYA). They were new test strips so I tried an older one from last year and the same results. I cannot explain it. I will take a sample to the pool store this week. What could cause this? I have shocked and am adding Chlorine through the skimmer. I do have a purple stain that worries me. From reading I guess this is from high CYA and cooper.
Thank you for any feedback. Good finding you all.