We are still in the process of converting from Baquacil to chlorine, but just wondering about something. In reading all about the BBB method and going back to chlorine, when is it appropriate to use algecide? When purchasing chlorine at the big box store, I picked up some HTH algecide which is supposed to last 90 days (thought that sounded like a good thing), but after reading it appears the suggested method would be to just shock instead of using algecide. So should algecide be used preventatively, only when algae is visible, or not at all-shock instead?