I saw it laying in the bottom so I vacuumed the pool on recirculate until I didn't see it anymore. I have vacuumed several time since on filter but have not backwashed. My water is crystal clear. I have added a ton of chlorine this wear. I added 6 gallons a day for a week then added more CYA, but never got a CYA reading and my chlorine level fell to 0 in about 4 hours. I shocked it with pool shock 3 of 4 times. I again added 6 gallons of chlorine a day for another week added more CYA and my chlorine level is still dropping to 0 with no CYA reading. I did open the pool in May with an algae problem I was adding 3 gallons of chlorine a day and it cleared up in two weeks. I continued adding the chlorine for additional week, Then started on try to raise CYA with no luck. I think I have added. I have added approximately 150 gallons of chlorine, pool shock, 8 chlorine plucks and 10 pounds of CYA since the middle of may.