The beginning of the year I added cya to 40, but I had huge problems with algea. I have backwashed and vacuumed to waste lots. We also had to drain off the pool about 5 inches 2 times because of heavy rains. I have had to add at least 2 gallons of bleach a day the past week. I tested my cya last night and it shows 0. I am going to add more cya tonight via a sock. Could of this had happened cause of all the lost water?