My pool looks great, but it uses about 3.5-4ppm/day of FC. I'm trying to get it down to around 2ppm/day so I'm thinking about raising the CYA. I've done the OCLT many times over the past few weeks, and it always shows no loss of FC overnight and 0-0.5cc, depending on the day. The pool gets full sun for most of the day. I just added 1pound of CYA a week ago, but there was not much change to the daily FC loss. The CYA test shows the level at 35 (exactly between 30 and 40 on the test tube). If I add another pound of CYA this afternoon to bring the CYA level to around 40-45, how long will it take for the CYA to become effective? I know it won't show up on tests for about a week, but is it effective before it shows up on the test? Thanks.