Environmentally friendly and economical heating of the water by solar energy. The PE film with air chambers floats on the water surface. During the day, the water temperature can increase by up to 4 - 8°C, depending on solar radiation, and at night the solar tarpaulin has an insulating effect and thus helps to reduce heat loss. Significantly reduces water evaporation and also protects against the ingress of dirt. The blue solar film is translucent and thus also allows the warming of deeper water regions. The shape and size of the film can be changed with the help of normal scissors.