All,

I have officially switched to the BBB method and turned off my auto-chlorinator! Due to my use of Chlorine Tabs my CYA reading is ~ 90. My other numbers are as follows; PH 7.6, TA 80. My pool is ~ 17,500 gallons and is an above ground vinyl liner using a sand filter. The water temp has been around 76 over the last couple of weeks.

Based on the high CYA I understand that I must keep my FC high (7 to 12 ppm range), but I am having difficulty maintaining this level w/o adding what equates to a gallon of bleach (6.0% or 8.25%) per day. As an example, at 6pm the other day my FC was at 4.6 so I added (2) 121oz jugs of 6% bleach. By 6:40 am the next morning my FC was 10.6 (expected), and by the next morning it was at 6.6 (not expected). So it lost 4ppm of FC in 24 hours. Is this typical? I like the thought of using the bleach, but this could get expensive if I am adding a 121oz bottle of 8.25% bleach (~ 4.5ppm raise in FC of my size pool) everyday.

At the end if the season (3 more months in the NE) I was going to wither drain / refill to lower the CYA or let it sit over the winter to see if the CYA reduces on its own. Is it easier to "maintain" FC with a lower CYA?

Please let me know if I am doing something wrong here. Thanks!