What is a pool skimmer, and how does it work?

Leaves, insects, pollen, and other debris tend to accumulate on the surface of a pool before sinking to the bottom. Preventing them from reaching the bottom is precisely one of the functions of the skimmer, a discreet yet essential component of the water recirculation and filtration system.

But what exactly is a pool skimmer? It is an opening typically installed at the top of the pool walls that draws water from the surface and directs it toward the filtration system. Inside, it contains a basket that traps larger debris before it continues through the system.

Therefore, if we ask ourselves what the skimmer is for, its main function is to collect floating debris and promote continuous water circulation. This helps keep the surface clean and prevents some of that debris from reaching the bottom or overloading other components of the filtration system.

The skimmer does not filter or disinfect on its own: it acts as a first line of defense in a process that also involves the pump, the filter, the return jets, and the water treatment systems.

Types of Skimmers for Commercial Pools

Not all facilities use the same type of skimmer. The choice depends on factors such as the pool’s dimensions and characteristics, the construction material, the recirculation flow rate, and the specific needs of each facility.

Among the most common types are:

• Standard skimmers: These are built into the pool wall and are one of the most common solutions for pools with skimmer-based recirculation systems.
• Wide-mouth skimmers: These feature a larger opening to expand the surface intake area.
• High-level skimmers: These allow the water level to be maintained closer to the top edge of the pool, a feature that can serve both functional and aesthetic purposes.
• Skimmers for prefabricated or panel pools: These incorporate fastening systems and gaskets adapted to the type of structure and lining.
• Stainless steel skimmers: used in certain projects where structural or aesthetic requirements call for this material.
• Filtering skimmers: combine surface water collection and specific filtration elements in a single unit.

In commercial pools, the selection should be part of the overall hydraulic design and should not be based solely on the size of the opening or the basket’s capacity.

How the Skimmer Works in the Water Recirculation System

Its operation can be understood by following the path of the water.

When the pump is running, some of the surface water enters through the skimmer inlet. A gate or float facilitates the collection of this top layer, where leaves, insects, and other floating particles tend to accumulate.

The water then passes through an internal basket that traps larger debris. From there, it continues through the suction pipes to the pump and the filtration system.

In systems that use sand filters for swimming pools, the water then passes through the filter media to remove smaller particles. Once filtered and treated, it returns to the pool through the discharge nozzles.

The orientation and distribution of these jets are also important: the goal is to create circulation that directs surface water and debris toward the suction points.

In this way, the skimmer, pump, filter, and jet nozzles function as parts of a single circuit. If any of them malfunctions, the overall efficiency of the recirculation system may be compromised.

Installation and Sizing Based on Pool Volume

Properly sizing skimmers requires looking beyond the total volume of the pool. Although volume influences the flow rate needed to renew the water, the water surface area, the pool’s geometry, the allowable flow rate per skimmer, and the hydraulic configuration of the system must also be considered.

As a general guideline, there are conventional models for which the manufacturer recommends approximately one skimmer per 25 m² of water surface area. However, this figure should not be automatically applied to every installation: the equipment specifications, the design flow rate, and the relevant regulations are what should determine the final solution.

Location is also important. Skimmers should be positioned so that surface water movement directs debris toward them, taking into account the position of the jet nozzles, the shape of the pool, and—in outdoor pools—factors such as prevailing winds.

In commercial pools, where flow rates and operational demands may be higher, sizing must be integrated into the hydraulic design from the outset.

Maintenance and Common Skimmer Problems

Although their operation is simple, skimmers require periodic inspections to maintain proper suction.

The most common task is to empty and clean the basket, especially when there are large amounts of leaves or other debris. If it becomes too full, it can restrict water flow and impair circulation.

It is also advisable to periodically check:

• that the inlet gate moves freely;
• that the water level allows the skimmer to draw water properly;
• that there are no leaves or objects blocking the inlet or the pipe;
• that covers, gaskets, and connections are in good condition;
• that all skimmers have balanced suction.

A water level that is too low can cause the system to draw in air, while a level that is too high reduces the skimmer’s ability to effectively skim the surface layer. A noticeable loss of suction may also indicate a clogged basket, problems with the pipes, or issues with other components of the system.

These checks should be incorporated into routine pool maintenance along with inspections of the filtration, circulation, and water quality parameters.

Ultimately, understanding the skimmer’s function provides a better grasp of the entire pool recirculation process: it captures surface debris before it settles and directs the water toward the filtration system. In commercial facilities, proper hydraulic design and correctly sized equipment are essential for achieving efficient circulation. Fluidra offers comprehensive solutions for water treatment and recirculation tailored to the needs of commercial and professional swimming pools.