What is a Pool or Spa Skimmer Used For?

Swimming Pool Parts and Maintenance

robotic pool skimmer
A robotic pool skimmer in a swimming pool. Flickr member Wicker Paradise

Think of a pool skimmer in a residential swimming pool like you would a gutter in a larger public swimming pool: it helps clean by skimming water and capturing floating debris like leaves, flower petals, dirt, twigs, dead insects, and oil (sunblock)― before the waste can sink to the pool's bottom.

Most skimmers on in-ground pools are built into its upper sides, where the suction draws debris and traps it.

Most pool skimmers are accessed via the pool deck area through a trap door or hatch. The skimmer is also in a convenient location to attach a suction line for a pool vacuum.

Skimmers for In-Ground Pools

A surface skimmer is typically made of plastic (or PVC) or precast concrete and has a tank with a projecting throat on its upper side. The skimming action is performed by the weir, which regulates the amount of water entering the skimmer. Since the weird adjusts to permit only a thin layer of water to spill over, water is pulled off the surface quickly―keeping a large part of the pool surface clear.

One skimmer that is positioned in a good location can keep about 500 square feet of its surface clean. If the debris gathered by the skimmer is left to accumulate, it can put additional strain on the pump. For this reason, among others, the skimmer basket should be cleaned out daily during swim season.

A skimmer must be installed with an equalizer line, which is a pipe that connects from the bottom of the skimmer basket through the pool wall and into the water. The equalizer helps to prevent air from being sucked into the system if evaporation causes the water level to drop below the weir level. Make sure air doesn't enter the system―it could cause the pump to stall.

Many pool skimmers come equipped with automatic water level controls and automatic chlorinators.

Robotic Pool Skimmers

In recent years, floating and robotic pool skimmers have entered the market and offer an alternative to a stationary model. Operated by batteries or solar power, these automatic skimmers float on the surface of a pool, collecting debris as it moves through the pool. Devotees of products like the Solar Breeze NX claim it cuts down on time and work, especially in areas prone to winds carrying leaves and debris into the pool or regions with lots of insects. It can also lower the cost of energy bills, as it is designed to work independently of the pool pump.

Other automatic skimmers, like the whirlpool-like the SkimmerMotion, is designed to connect to an automatic pool cleaner (vacuum), then collects surface debris as it floats through the pool. Debris is sent to the pool's filtration system.

Adding Chlorine Tablets to a Skimmer

While some pool owners claim that placing those chlorine tablets―known as hockey or chlorine pucks--right in the skimmer basket cuts down on time, many pros advised against this. The high concentration of acid can break down parts of the filter, possibly causing a need for more frequent replacement.

Above-Ground Skimmers

Because above-ground pools have thin walls, floating pool skimmers are most often used, as are units that hang on the pool's edge. To keep skimmers for above- and in-ground pools working properly, try to clean out the skimmer basket daily during swim season.

Skimmers for Spas and Hot Tubs

Skimmers for redwood hot tubs usually have no basket; instead, skimming the surface and pulling debris to a plastic screen. Some portable spas have skimmers with built-in cartridge filters.