I've never added stabilizer to my pool and I can't measure any CYA using the Taylor test kit.
Last week I measured ORP and FC using the Taylor FAS-DPD test before, and after, the pool was exposed to one hour of direct, overhead sunlight. I saw no difference in either ORP or FC during that hour!
Today, is a sunny, low humidity day in NC. I just did 6 FAS-DPD drop tests over the hour when the sun was directly overhead. Again, I see no measurable difference in either FC or ORP.
When I was only using copper ionization between weekly shock treatments, I could see the copper PPM decay when the ionizer setting wasn't high enough. It would decay to near zero in a few days, when the ionizer was off completely. However, now the ionizer has been off for a week with very little, if any, decay in copper PPM.I do have .3 ppm of copper in the pool, even though I turned the ionizer off a week ago. Is it possible the copper protects the FC like CYA does?
Maybe the copper gets depleted when it does the disinfection and now that there's FC, the "load" on the copper is lower? Is there another explanation why the copper could be observed decaying with a 1/2 life of one to two days, while now I can see no decay in a week?
Water temp 79
CYA stabilizer never added, dot clearly visible in Taylor test which implies < 30 ppm.
copper .3 ppm
iron 0 ppm
Any ideas why I don't see anywhere near the expected FC decay rate?