Hi, Sandy,

When I add high doses of Cl, I do it at dusk (full shade is pretty good, too). That pretty much eliminates the Sun from robbing your Cl and let's the majority of it work on the bugs. I simply do not add it during the day because the Sun eats it up and I'm cheap.

It would be fine to add CYA but, if you're cleaning your cartridge pretty frequently, you'll wash it out of your filter before it dissolves into your pool. You could certainly put it in a sock and suspend it in the water. If so, I'd put in enough to raise it by 20ppm more.

Since your pH shows a tendency to creep up, I would add enough muriatic to shoot for 7.0 - 7.2........measure accurately. It'll make your Cl that much more effective on the bugs.

Synopsis - keep up the Cl - evening application is most effective - CYA if you choose - bring pH down to the lower range of 7.0-7.2