Pool Central 18 ft. Round Heat Wave Solar Pool Cover in Blue

18 ft. Round Heat Wave Solar Blanket Swimming Pool Cover - Blue. In fact in some areas of the country a good quality solar blanket may be all you need to warm your pool water and make your pool more enjoyable. Extends swimming season by up to 6 weeks. Solar blankets are made from a durable polymer material with thousands of tiny sealed air bubbles. They float in. bubble side down in. on the surface of your pool water when the pool is not in use and allow solar energy to pass through which is then trapped as retained heat in the pool.