Recently had to switch to 8.25% bleach because of murky water (due to be changed) and the CYA level creeping up high (currently 85) and us newbies not accounting for needing to have a higher FC to combat that until we dump.
Got the water cleared up thanks to all the help here. Friday nite (4/24/15) the FC was 15ppm. We went in the tub for 40 minutes (so 1.2 person hours). Added 1/4c of 8.25% bleach afterwards which according to pool math should have taken it up 5.3ppm.
Last nite we tested at 7:45pm and the FC was 9.5ppm.
So if it was 15ppm on Friday nite before soak and then we added enough bleach post soak to take it up 5.3ppm that should be roughly 20ppm and then almost 24 hours later it was back to 9.5ppm. What exactly does that tell me? Did that 1/4c not do enough for us to deal with general losses plus bather load cleanup?
So after reading 9.5ppm last nite, we added another 4oz of bleach at 10pm which should have put us back in the 15ppm range. Didn't go in the tub.
Just now did our weekly testing at 1:45pm with these numbers:
pH: 6.8 (tho no aeration so I'm somewhat ok with is being low I think)
CYA: 85 (I know this is too high, we just don't have time to dump right now)
So in 16 hours with no one in it, the FC came down by 50%?? That seems bad but perhaps it's still cleaning up little bits of things even tho we shocked the heck out of it when the water was cloudy. On the CYA chart 7ppm is the minimum with 10ppm being the target so I'm thinking I should add in 2oz of 8.25% bleach to take the FC up 2.7ppm. But then I don't know how much to put in after our soak (probably 1 to 1.2 person hours) tonite.......
Thanks for helping me interpret this stuff.