Amazing how when you come to the pool store with an algae problem and you have a vinyl pool, they INEVITABLY "recommend" (ie sell you) calcium--and then recommend using Cal-Hypo to chlorinate. Calcium is USELESS in a vinyl pool! And the Cal-hypo adds even MORE calcium that you don't need.

Now Cal-Hypo, used appropriately, is a fine product, and a good way to shock a pool that isn't already high in calcium. But it's irritating to us that pool stores CONSTANTLY push calcium to customers with algae problems when it cannot help at all.