Ultra Bright worked very well for me. My pool had red clay dirt in the water after installation and after holding 3 nights on the overnight chlorine loss test, I used it and my pool went from barely seeing the vacuum head on the bottom to perfectly clear in one day. The skimmer sock was barely catching any of the dust before I started to turning the sock completely clay red and having to cleaning it 3 times on that day. I used 2 doses, but I think I should have waited 24 hours to see if I needed the second dose.
With that said, on Monday I added 1 ½ lbs of CYA through pantyhose in the skimmer and I haven’t registered any increase yet. I don’t know why.