After you get the stuff on the bottom dissolved, recheck you CH. I've read how you can minimize the amount of calcium added to a pool but mixing cal-hypo in a bucket of pool water and pouring it into the pool until you start getting some slurry. Mix it again and pour again until you get slurry, then toss the rest. I guess the calcium dissolves slower than the "hypo". Maybe that's what's on the bottom of your pool - or other unknown stuff like CarlD describes in "cheap" products.