adjust cya before or after shocking

[PoolDoc]

Bleach loss during the day is likely sunlight. You can really only tell what your non-solar loss is, by comparing late PM to early AM readings.

What is your CYA level?

[Kateyru]

The last time I checked CYA was 5/8 and it was 40. I've been following Janet's recommendation to focus on FC and not worry about anything else. This morning at 6:30, FC was 16.5 and CC = 0. I had not been checking CC but did today since Watermom said to. I added 3 more qts of bleach and turned SWG on as I was not sure I could get home until late afternoon. Trying to make sure FC stays over 15.

[PoolDoc]

Do you still have visible algae?
Where? What does it look like?

Also, it's probably time to retest your CYA level.

[Kateyru]

No visible algae. Water looks good, nice and clear. I'll retest CYA this afternoon. Do you think I can let FC drift down or do I need to keep it at or above 15 for another day? Am really hoping for a clean pool by this weekend!
Thanks so much!

[Watermom]

Go with another day for added insurance. If after one more day, you still don't lose more than 1ppm overnight and still have CC of 0, let it drift down. But, be diligent about keeping your chlorine levels at appropriate levels based on your CYA reading. (Like Ben said, retest CYA to make sure you know what it is so you'll know needed cl levels.)

[Kateyru]

Okay, FC last night and this morning were the same and CC was 0. Doing insurance plan today If FC and CC are okay from tonight till tomorrow am, I'll let chlorine start the downward drift. CYA was 45 to 50 last night. I'm struggling with reading CYA and trying to accurately recognize "just till black dot disappears." I haven't had problems with chlorine levels in the past but plan to up CYA to 70 to 80 so will be more vigilant and diligent re: chlorine as needed.
thanks again for all the help. I just read "the history" of the forum. I am so glad the forum (and troublefree pools website) exist and very, very glad I found both!

[aylad]

Just don't ever let the chlorine get below 3 ppm, and if you up your CYA any more, then don't let it get below 5 ppm, and you shouldn't have any troubles.

The CYA test is a very subjective test--the best you can do is try to run the test in the same conditions (lighting, distance from tube to your eye, etc) so you can be as consistent as possible.