Moved to a new topic. If there is any chance of hijacking, please start a new topic. JasonLion
Sorry to hijack the thread, but I was going to post the exact same question. I am using the TF test kit in a 19,000 SWG inground, vinyl pool. I added 4 pounds of stabilizer at the beginning of the year per the pool store recommendations then, through a miscommunication my son added another 4 pounds. After that i switched to doing my on tests using the TF kit. At the end of May my CYA was 30, and stayed there for the next 2 weeks, testing once a week. last night it was down to 20. What happens to the CYA? I have lost about 4-6 inches of water through evaporation (warm sunny days, cold nights here in VA. I use a solar heater which raises the temp 10 degrees during the day) So if I don't have a leak and I don't backwash because I have a cartridge and I have not added water, what happened to the CYA? Is it possible the test is not accurate?
I have also noticed a drop in TA from 130 to 90 over the same period. I used to use the local pool store(s) for testing but got frustrated with contradictory results so I bought the test kit and am now trying to understand chemistry.
Thanks for opinions.