The Covrex® Solar shutter heats the water by absorbing solar heat.
It is the rays of the sun that heat the black lower part of the blade as well as the air which is in the hollow chambers of the blades. The heat is then directly transmitted from the sun to the water in your pool. This is a continuous and completely free energy supply! In addition, the fact that the lower part of the blade is black, this greatly limits the entry of sunlight into the pool, and therefore reduces the proliferation of algae in the pool.
Keep a filtration when the shutter is closed, in order to distribute the heat evenly from the surface of the water to the rest of the basin.