I've noticed these white translucent particles floating in the water the other night when I had the lights on. They are flat and 2 to 3 millimeters square or rectangular. I can't detect them during the day - only at night just in front of the lights. I noticed it the most after brushing the pool as I probably stirred them up. I can capture them with a net and they are soft and fall apart when touched. I'm guessing its calcium, but my CSI has never ventured out of range (-.6 to .6) and is almost always around -.3. All numbers are in range for a SWG plaster pool. Any ideas? I'll try to get a photo.