Split off of this topic. JasonLion
Thank you for correcting me Jason, I'm still a grasshoppa! I didn't think about the FC dropping to 0 during the day. I figured it would be so quickly used up oxidizing that it wouldn't matter.
So hypothetically with CYA at 0, if the shock process was started with bleach right after sundown and maintained for about 8 hours wouldn't that be much more effective at killing organics considering the higher hypochlorous acid levels? Or is the FC/CYA equilibrium aggressively maintained enough to kill everything just as fast AND have the UV protection?
If it IS more effective at 0 CYA, then doing the initial round of shocking after sundown would speed up the conversion process, right? Before sunrise, shocking could continue with dichlor into the daylight hours, yes? One could easily figure out the amount of dichlor needed to bring the CYA up to 30ppm and then stop using it once you've added that much and switch back to bleach.
Another thing to worry about is bleaching the liner the first night with the higher levels of hypochlorous acid. Reading chemgeek's Chlorine/CYA Chart I see that at 0 CYA the shock level is technically only 0.64ppm but that leaves no reserve. So, what is the upper limit safe level of FC at 0 CYA without bleaching the liner?