I've been using this for two seasons on a pool I inherited with home purchase. Pool was extremely nasty but cleared up with the baquacil cdx system. Expensive to use. I used the step 3 algaecide years ago with good results. The pool store owner said that the step 3 cdx is a rip off and doesn't sell it- only sells the algaecide step 3. I read that the cdx maintains the oxidizer level which is quite high in my pool. I continue to use even with the cost because I have had no problems and only need to do weekly tweeking of chemicals.