Is this in addition to shocking with the 8.5 gal I already have or instead?

Sorry if that's a stupid question, but I don't want to mess this up. Like I said, our water finally looks amazing, but the FC dives to almost nothing each night.

Then do i add the CYA when i get back to get our number closer to the 80ppm Aqua Rite recommends for our SWG?

Thanks again!!!