Trichlor tabs are stabilized meaning that they have CYA in them. For every 10ppm of chlorine they add, they will also add 6ppm of CYA. So, you can use the tabs for awhile and then when you get your CYA where you want it, discontinue them and switch to a non-stabilized form of chlorine like bleach. BUT....... Make sure that your tabs have NO copper in them! You don't want copper in your pool! Contrary to popular belief, it is copper and not chlorine that stains pool surfaces and turns light-colored hair green!