Blue Horizons Ultimate Winter Time is a copper-free algaecide designed to prevent algae growth in outdoor pools from fall to spring. One dose can keep your pool algae-free for up to 6 months, reducing the likelihood of staining and scale deposits. Algae are plants that can multiply quickly, rendering costly and time-consuming recovery efforts necessary. Our algaecides are specially formulated to guard against many types of algae, and we offer both weekly dosed and long-life versions for your pool maintenance needs. The long-life algaecide is an effective copper-free summer algaecide that prevents stains and scale and is compatible with chlorine, bromine, and biguanide treatments.