My pool was clear and balanced, I added liquid chlorine and suddenly black sediments and mucasy substances appearred and came to the surface. The pool turned black and enormous ammounts of sediment appeared. Just massive amounts. I am very experienced and have had this specific fiberglass pool for 7 years. I have vac to waste everyday and have gotten thick sludge one day orange black the others. It is not FC or algae or CYA. It has been raining everyday but the pool is enclosed and nothing is running in. The FC is extremely high because I added a lot more after the first couple of days before looking at CYA. I do have a heater but never had any thing at all like this previously.