Does CYA 'degrade' at any sort of average rate?

[Watermom]

Cleaning the filter can make you lose your cya if you have recently added it. But, really, after about a week or so, the cya should have all dissolved and from then on, cleaning the filter should have no effect on cya levels.

[waterbear]

As a side note, trichlor is probably more successful with sand filters because the constant backwashing keeps diluting the pool and the cya level doesn't rise as fast. With a cartridge filter and trichlor it can only be a matter of months before the cya is way too high. I have personally seen these trends in the testing histories of the customers at the pool store I work at.

[Henrys514]

With a cartridge filter and trichlor it can only be a matter of months before the cya is way too high. I have personally seen these trends in the testing histories of the customers at the pool store I work at.

That's good information to know. My husband used to use trichlor a lot during our first pool season (2 years ago). I found some old printouts from the pool store the other day, and our CYA was ALWAYS high...like around 90-100ppm.

[VOLDADDY]

About backwashing and losing CYA, just do what has been recommended here and add it to a sock or panty hose. I do this and tie it to the ladder in the deep end of my pool, in front of a jet. It usually takes about a week for it to fully dissolve. This way, you can backwash as often as you wish and it doesn't diminish your CYA.