Quick update in case it can help others. The Sink & Sweep worked very well. I ended up doing two treatments/vacuums to waste, but found out later from my pool servicer that floc stays in the water a while, so the second dose might not have been needed. After round two, I let the water settle a few hours and it looked clear enough to restart regular filtering. In all, it took five days to completely get the clay out, but surprisingly, I only need some minor balancing. Thanks again for the advice.