The pool people are in this to make money....we're not. You don't need the oxygen shock at all. If you maintain proper chlroine levels, you won't need the algaecide, either, but some of the forum members dose with it (ONLY if it's 60% Polyquat--no other kind) when closing their pols. And no, you don't have to use the pucks at all, either. In fact, when your stabilizer levels get to the point where you're holding chlorine in the pool, the pucks are actually detrimental. With a vinyl-lined pool, you can safely and efficiently maintain a crystal clear pool using bleach, muriatic acid, Borax, and baking soda. My pool is vinyl in-ground, open year-round, and that's the recipe I use, with a little boost from the trichlor pucks.

Janet