The more dark bubble cover, the better for your swimming pool! Less light in the water means worse conditions for the algae growth. Elegant and perfectly made solar bubble cover is made of blue, rigid foil LDPE with thickness of 400 microns. On the surface has a numerous air cells (bubbles), which prevent heat loss and facilitate heating of the water. In the unheated pool, the bubble cover allows to raise the temperature by about 6 degrees.