I am looking after a pool for a person who just bought a house with a pool. I had the water tested and the cya was 170. I drained about 40% and had it retested as being 110 at a pool store. Then I drained and refilled another 40% and got a 50 test at the pool store. Then the next week I had it tested again and it came back with a score of 99. Is the test faulty do you think or has there been a secret cya fairy come along and added cya.
Highly variable CYA test results at pool store
- Thread starter Ajpm77
- Start date
I bought my house with pool last September, I found this site but didn't take it all that seriously, took some info left other. My pool was running inline chlorine tabs for who knows how long. I have test sheets from using the pool store(s) going back to October 2016, some of the readings were good but every single CYA reading was wrong, some off by almost 200. They never diluted the test, they test indoors, and most importantly they didn't take the CYA/FC relationship in account at all when giving advice. Best bet is to get the Taylor 2006c or tft 100 and learn the TFT way to take care of your pool. Or you can wait until you have more problems like I did and then finally come around 
We don't trust pool store testing. We always recommend that owners get their own test kit and test themselves
"99" is pool store code for "off the chart"
That being said, I don't believe it. Unless you've been dumping bag after bag of dichlor shock into the pool, it can't double in a week.
That being said, I don't believe it. Unless you've been dumping bag after bag of dichlor shock into the pool, it can't double in a week.