G game Well-known member Jun 1, 2017 61 Dunn, NC Jun 24, 2020 #1 What would cause my Chlorine reading to go up overnight doing the OCLT. At 11:00 I took a reading off 22.5 . Now at 5:45am the reading is at 25. Yes, abuse the FAS-DPD kit. New sand put in our filter before starting SLAM.