C cool4pool Member Jul 1, 2017 16 Baltimore, MD Jul 4, 2019 #1 My readings this morning: FC 3 pH 7.8 TA 80 CH 250 CYA 60 Salt 3100 Water Temp 86 CSI -0.07 Water is clear. Pool looks good. Working on getting the CYA and FC up alittle more. However, when I go to either skimmer I find the black particles in the attached picture. Any idea what this is?