Q: Where exactly was the sock placed? How many lbs. of stabilizer did you place each time and how long did it take to dissolve?
Is it possible, that the stabilizer (CYA) dissolved or was sent to the filter in clumps? And that is where it is slowly dissolving and could take longer? Can you find your receipts to determine exactly what you purchased, when you purchased, and how much you purchased? This could create a timeline and you can obtain more accurate data. Your wrote in your first post "Probably".
Could cleaning the DE filter have removed any CYA, that did not fully dissolve in the pool?
Is it possible, that the stabilizer (CYA) dissolved or was sent to the filter in clumps? And that is where it is slowly dissolving and could take longer? Can you find your receipts to determine exactly what you purchased, when you purchased, and how much you purchased? This could create a timeline and you can obtain more accurate data. Your wrote in your first post "Probably".
Could cleaning the DE filter have removed any CYA, that did not fully dissolve in the pool?