So, what else can you do to protect your solar pool from cooling and to keep the water as warm as possible? First of all - use a pool cover.
Pool cover
Pool cover or pool blanket is basically a sheet of plastic which stops water evaporation from the surface of a pool. Evaporation is by far the largest source of energy loss; it is responsible for approximately 70% of heat loss from your solar pool. Evaporation rate depends on the pool’s temperature, air temperature and humidity, and the wind speed at the pool surface. Please note that the dry air contributes to more heat loss compared to the humid climate. By covering your pool with a waterproof plastic you isolate it from the direct contact with wind and air and “bring back” the vapor from the surface which, in fact, contains the major amount of heat energy in it.
The situation is more entangled during the day time. From one side, if your solar pool is exposed to the sunlight, the water absorbs about 80% of solar energy and gets warmer. From the other side, the evaporation losses make the water cooler. When you cover the pool you eliminate these losses but at the same time you reduce the amount of sunlight which is being absorbed. Thus, different results are achieved with different covers.
Types of pool cover
One of the cheapest covers made specifically for swimming pools is the bubble cover. Bubble covers are similar to bubble packing material except they use a thicker grade of plastic and have UV inhibitors. In addition, there are various vinyl covers made of a heavier material with a longer life expectancy compared to bubble covers. Insulated vinyl covers are also available with a thin layer of insulation sandwiched between two layers of vinyl. All of these covers are made in a form of a big sheet you need to cut to match your solar pool surface.
Some pool covers are made as thin plastic sheets floating on the surface of a pool. They are quite small in size and each sheet protects only about a square meter of the pool’s surface. They can be of rectangular or round shape and you can buy as many as you like to cover your pool. This solution fits pool of any shape covering about 70%-80% of its surface.
Which one to choose?
There are several factors you should pay attention to while buying a cover for your solar pool. The cover should be made of a strong plastic resistant to sunlight (including UV radiation), water, and various chemicals (if you use any in the pool) and it should serve you for at least three seasons. Moreover, if the cover is transparent it should pass as much as possible sunlight into the pool. If the cover is opaque it should transform absorbed sunlight into heat and radiate it into the pool to reduce the obscuring effect.
You may also consider two different types of cover for the night and the daytime.
