Pro-Kleen Winteriser is designed to maintain your pool over the winter period. It helps to keep your pool free from limescale, algae and mineral staining, making it much easier to prepare your pool to use in the warmer months. Our unique formula is completely safe to use in all whirlpools, spas and pools and provides incredible results! For ease, theres no need to empty and/or refill your pool before use simply add the formula into your pool water and itll get to work straight away to protect your pool from the harsh winter conditions. ProKleen Swimming Pool Algaecide Winteriser 4 x 5L in Clear