Had some unusually high chlorine demand (for no apparent reason, but that's another issue) so started down the shock path. Mind you, through this entire process, CC has never been over 0.5.
I lowered the pH to 7.2 or 7.1. First question - that's a good level to start with, right? Is it okay if I slightly overshot the pH lowering?
Now, the numbers...When I do the math myself, 121oz jug of 8.25% bleach in my ~15,500 pool (mind you I'm 100% sure on the pool volume), I get that it should raise the FC by 5.03ppm. But the pool calculator says it should be 5.2. Does anything else affect the FC numbers?
So, about that bleach...I measured the pool at a little over 6FC and, with my CYA at 50, the pool calculator says shock level would be 16. So I figure 2 bottles of the 8.25 to start and go from there. But after the 2nd bottle and letting it circulate (poured it slowly in front of jet, let pump run at full speed) for 30-45 minutes, the level I got was 21! I took my sample from the opposite end of the pool, but did I let it circulate long enough? And by overshooting so much, is that an issue?
Regardless, we're off now, so I let it go over the day yesterday and check the level at night. It's all the way down at 14. So, using the pool calculator, 72 ounces of 8.25% bleach should raise me by 3.1, which will get me to 17, which should be good. But, after the same process (slowly pour in front of jet, let circulate for 30-45 minutes), my FC is all the way up to 21! Instead of raising it 3, it raised it 5! Huh?
Okay, well, either way, it's at shock level, let it roll. I test it this morning and it's at 18.5. CC was 0.5 or 0 (honestly don't remember right this second), but a 2.5 drop in FC. I'm still over shock level, so I'm not adding any more bleach. But can anyone make sense of all this for me? I'm extremely confused about the above...