A skimmer or surface separator (it separates substances from the surface of a liquid) is an essential accessory for the maintenance and cleaning of the water in a swimming pool. It is used to remove all the surface dirt floating on the water surface, such as leaves, tanning oil and human secretions. These impurities remain suspended on the surface, affect the appearance of the water and are not always removed by the conventional vacuuming process. The skimmer is installed directly in the surface water suction system and also has the function of controlling the water level to prevent accidental overflows. In the United States and Portugal, the use of skimmers in the construction of swimming pools is mandatory, regulated and standardized by competent bodies.
Types There are different types of skimmers that can be used for different purposes. The most common types of skimmers include:
Manual skimmers: These are basic skimmers that consist of a strong net strung on the end of a long pole. They are used to remove waste and pollutants from the surface of the water. Automatic skimmers: These are the most common variety of skimmers and are most likely seen running in any given pool. They are installed at surface level and are designed to remove debris and contaminants from the surface of the water. Standalone skimmers: These skimmers are designed to be used in conjunction with a pump and filter system. They are installed at surface level and are designed to remove debris and contaminants from the surface of the water
Drainage opening
Typically a skimmer draws water from the pool through a rectangular opening in the wall, at the top of the pool, connected through a device installed in one (or more) walls of the pool. The internal parts of the skimmer are accessed from the pool deck through a circular or rectangular cover, approximately one foot in diameter. If the pool's water pump is operational, it draws water from the pool through a hinged floating chute (which operates from a vertical position at a 90-degree angle to the pool, to prevent leaves and debris from being washed back into the pool by wave action), and down into a removable "skimmer basket", whose purpose is to catch leaves, dead insects and other larger floating debris. The opening visible from the side of the pool is usually 1'0" (300 mm) wide by 6" (150 mm) high, which cuts the water halfway down the center of the opening. Skimmers with wider openings are called "wide angle" skimmers and can be up to 2'0" wide (600 mm). Floating skimmers have the advantage of not being affected by water level, as they adjust to work with the suction rate of the pump and will maintain optimal skimming regardless of water level, leading to a significantly reduced amount of biomaterial in the water. Skimmers should always have a leaf basket or filter between it and the pump to avoid clogging the pipes leading to the pump and filter.
Consecutive dilution A consecutive dilution system is usually provided to remove the organic waste in stages after passing through the skimmer. The waste material is trapped within one or more sequential skimmer basket sieves, each with a finer mesh to further dilute the size of the contaminant. Dilution here is defined as the act of making something weaker in strength, content or value. The first basket is placed very close to the mouth of the skimmer. The second is connected to the circulation pump. Here 25% of the water drawn from the main drain at the bottom of the pool meets 75% drawn from the surface. The circulation pump sieve basket is easily accessible for maintenance and should be emptied daily. The third sieve is the sand unit. Here the smallest organic waste that has slipped through the previous sieves is trapped by the sand. If not removed regularly, organic waste will continue to decompose and affect water quality. The dilution process makes it easy to remove organic waste. Ultimately, the sand screen can be backwashed to remove smaller trapped organic debris that otherwise leaches ammonia and other compounds into the recirculated water. These additional solutes eventually lead to the formation of disinfection byproducts (DBPs). The sieve baskets are easily removed each day for cleaning, as is the sand unit, which should be backwashed at least once a week. A perfectly maintained back-to-back dilution system dramatically reduces the build-up of chloramines and other DBPs. The water returned to the pool must have been cleaned of all organic debris larger than 10 microns in size.
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