Rapid Chlorine Loss


Jul 5, 2020
Levittown, PA

We finished a slam of our pool, first time owners, first time slam and could not be HAPPIER! However, we noticed that during the day we lose quite a lot-- more than I feel I've read is "normal" of Free Chlorine. For example, we could bring our FC to 15 based on Pool Math app and our 12.5% bleach in the morning and our midday test (between 1-2PM) would read like 7 or 8. Bring it back up to 15 and by our 9pm sundown read, back down to that 8ish. OVernight, we were continually bringing it up to 15, and it would be at 14 in the morning. We recently got the Dolphin E10 and since using that every other day with our brushing and backwashing, and two large rainstorms, we are noticing that we are losing more at night again. SO we "restarted" the slam since it now isn't passing the OLCT. Our CC is always negligible with barely any "pink" so one drop clears it right back up. We use the Taylor K2006 kit and so we are still making sure we keep it at slam level.

SInce 9PM last night, we have had to use over 2 gallons of the bleach compound. it just seems excessive to be losing as much as we are. Our most recent test is
FC- 7.5
TA- 90
CYA-37... (that CYA we tested about 30, but the 37 was from local pool store test on the last 3 occasions since the beginning of July-- we haven't added more since we were slamming and figure it kept our slam level at around 12-15, but are now thinking we should)

The pool is in full sun all day long, and temps have been in the 90s, with high humidity levels as well-- could this account for SIGNIFICANT loss or are we missing something?? We are still keeping it at shock levels so that we can be sure we are keeping it sanitized well.

Here is my day breakdown- this morning we had significant loss from our attempt to bring to 15ppm last night (added 122oz of 12.5% bleach at 9PM), 8:30AM FC was 7, added 93OZ of bleach, at 11:30 it was 10.5 so I added 52oz of bleach, at 4:45 the FC is at 6.5.....

Any suggestions--or are we doing the right thing by keeping the levels high, putting them back up 3X a day?


Gold Supporter
May 20, 2020
Katy TX
Pool Size
Liquid Chlorine
With your low CYA, the sun is eating up your CL. Can you increase it a little based on Pool Math recommendations?