adjust cya before or after shocking

[Watermom]

lease test FC, CC, and pH add bleach if FC is below 15 and get a FC reading at dusk so we can see how we're doing at dawn.

Dave, she reports in her post above that her CC was 0 and she had no chlorine loss overnight.

Katey, if tomorrow morning you still show no more than a 1ppm drop and still no CC, then go ahead and let the cl drift down and you can bump up your CYA if you wish.

[Kateyru]

H2O Ma, you're back...so if I have more than a 1 ppm drop or more than .5 CC, I'll need to add bleach, right? Just trying to make sure I'll know how to proceed.

and do I turn SWG back on in the morning?

[Watermom]

Yes, If more than a 1ppm drop or CC greater than 0.5ppm, then you're not done and you'll need to add bleach. Otherwise, let the cl drift down. Keep your SWCG off until your cl drifts down. No reason to waste your cell life.

[Kateyru]

got it, thanks!

[BigDave]

If you have no more than 1 ppm FC loss overnight (with the SWCG off), your CC is at or near 0 and the water looks clear; you can let FC drift down. The complicating factor here is that we lost no FC last night but the SWCG was on so... we lost as much FC as the SWCG produced overnight.
If your FC is 14.5 or higher in the morning then we're done with the algae battle and you can let the FC drift down.
If you can't watch it tomorrow and your FC in the morning is 14.5 or below, add some bleach to get above 15 and turn on your SWCG. Run another FC / CC test when you get home and let's take it from there.

[Watermom]

Good catch, Dave. With the SWCG running, you can't tell if there was no chlorine loss overnight or if the SWCG made up the difference.

[Kateyru]

Yesterday morning (6 am) FC was 14 and CC = 0. I did not add bleach (sorry--too early and too much of a hurry to check Dave's post)). Pump is running 24/7 but SWG is still off. Test results this morning were FC = 10 and CC = 0. Water looks good. Do I need to add bleach and get back over 15 again?

[BigDave]

Not necessarily. Test FC tonight when the sun is off the pool, and again early tomorrow morning before the sun is on the pool.

If FC is the same or within 1 ppm then you're done!
If FC drops by 1+, we'll need to get back to shock level.

Do you still have a supply of dichlor?
Pump / filter on - SWCG off.
How's your filter pressure?

[Kateyru]

I have 3 1/4 lbs. of dichlor. Filter pressure remains steady. Do I need to leave pump on 24/7 till tomorrow am?

[BigDave]

Is filter pressure steady at the same pressure as clean or higher than clean but not high enough to backwash yet?
Let's leave the pump on.