Hi! Jumping in here. Not sure where to post. You may have covered this but My head is spinning. I do not remember having such an issue about CYA any time before. My pool was refilled about 1/2 way this spring due to a now repaired tear in liner. Pool was horribly green to start. Used those socks in basket and caught amazing amounts of green algae. Pool looks blue but cloudy. Can't see bottom even in shallow part. Still can see dot at 90 on cya test. I have emptied out water twice to bottom of skimmer. So should be mostly fresh water! Still can see at 90. pH 8.0 easily. Did acid demand test. 8 drops to lower into range. Said see treatment tables (Taylor kit) and they aren't all that helpful. Initially I thought my shock level was 16. Now 35. Impossible amounts of bleach!!! The pool is over 1/2 fresh water. No shock or tablets used. I did use 1 bottle algaecide I had left over from pool company last year when I took cover off to swamp. What am I doing wrong? Was it the algaecide? Does it have that much cya? Can't tell from bottle. Sorry so wordy. Trying to tell you every thing you might need. Appreciate getting set straight. I did so well last year. Already need to reorder cyanuric reagent (by the gallon!).