I see others have posted similar issues with a very high chlorine demand, but wanted to post my own message with my own specific levels and such as I understand each pool situation is different. Let me give you the facts, and hopefully someone will see something that isn't right and make a recommendation for me.
I have a brand new plaster pool (22,500 gal) and I'm a semi-recent convert to the BBB method. In previous posts I have explained how I used the pucks and granules for the first month the new pool was in operation, but since then (end of June) have been religiously following the BBB method - mostly just adding chlorine (and a bit of baking soda twice to raise alkalinity and some calcium chloride recently to raise CH a bit).
My pH is very consistent at 7.6 (maybe 7.5 - not sure I'm interpreting the color correctly). In fact, I never even got a the huge spike in pH the PB said I would at startup, and so I've still got lots of pH Down on the shelf.
My CYA level is 60 (explainable based on the calculation of the amount of CYA introduced from the pucks and granules I was formerly using).
Based on this, I've been targeting FC of 7 and adding at least a gallon or so of 6% WalMart bleach daily - following amounts based on PoolCalculator.
I can also confirm that I've never gone over 0.5 CC in any given day, and most days it registers zero.
Living in a new development, there are no trees to speak of in the immediate vicinity of the pool and so it gets a full day of sunlight, with temperatures here averaging in the 80's (pool temp usually 85).
Last night at 7pm I measured my FC at 4, so added 140 oz of bleach to raise it to 7. At 10pm I measured again and was glad to see it was right on the money at 7. This morning at 9:30 (sun had already been up for a little while) I measured FC at 4.5 with .5 CC (no CC at all on yesterday's testing). Tonight at 6pm I measured yet again and got an FC of 2.5 and .5 CC.
Is it really possible for the sun to be using up THAT MUCH of my chlorine on a daily basis? There's been NOBODY in it during any of this time (usually only used on weekends).
So to provide the full picture, here are all of my current levels as of just now:
FC - 2.5
CC - 0.5
TC - 3.0
pH - 7.6
TA - 80 (very consistent)
CH - 210 (was 180 about two weeks ago but brought it up to 250 and it's been that way till this new test today)
CYA - 60 (I'm still a bit inconsistent with my CYA testing, but it's usually between 50-60)
Temp - 86
I'm adding 210 oz bleach right now to boost again to 7.
Any other suggestions? I'm seriously contemplating a SWG or Liquidator as the jugs are getting really old - can't keep enough of it on hand.
P.S. Otherwise, the pool has been crystal clear since the day they filled it and have never seen algae or had any other major issues.