Most pool and spa owners see the skimmer every time they use their water, but many do not realize how important this relatively simple component is to the entire circulation and filtration system.
A properly operating pool or spa skimmer helps remove leaves, insects, oils and other floating debris before those contaminants sink to the bottom or circulate throughout the system.
It also provides one of the primary paths through which water is pulled from the pool or spa and sent toward the pump and filter.
When the skimmer is working correctly, it quietly performs its job in the background. When something becomes clogged, damaged or improperly adjusted, however, the effects can quickly become noticeable.
Understanding how skimmers work makes it much easier to maintain them, troubleshoot circulation problems and identify the correct replacement parts when something wears out.
What Is a Pool Skimmer?
A pool skimmer is a suction opening located near the waterline of a swimming pool.
The skimmer is connected to the pool's circulation plumbing. When the circulation pump is operating, water is pulled through the skimmer and toward the filtration equipment.
Because the opening is positioned at the surface, the moving water draws floating debris toward the skimmer before it has an opportunity to sink.
That debris is usually captured by a removable basket inside the skimmer housing.
The basic process is:
Pool Surface → Skimmer Opening → Skimmer Basket → Suction Plumbing → Pump → Filter → Other Equipment → Return Jets
This continuous circulation helps keep the pool surface cleaner while delivering water to the filtration and treatment equipment.
Why Surface Skimming Is So Important
Many contaminants initially enter a pool at the surface.
These can include:
- Leaves
- Grass
- Insects
- Pollen
- Dust
- Hair
- Body oils
- Sunscreen
- Other floating organic material
If these contaminants are removed while they are still floating, the filter and pool cleaner have less work to do.
If they are allowed to sink, they may collect on the pool floor, enter other suction fittings or begin decomposing in the water.
Effective skimming therefore helps both cleanliness and overall water management.
What Are the Main Parts of a Pool Skimmer?
Skimmer designs vary by manufacturer and model, but most include several common components.
Skimmer Body
The skimmer body is the main housing installed into or behind the pool wall.
It contains the basket and connects the waterline opening to the suction plumbing.
The body may include one or more plumbing ports depending on the design.
Skimmer Basket
The skimmer basket captures larger debris before it reaches the pump.
This is one of the most important serviceable components in the skimmer.
A properly fitted basket can catch:
- Leaves
- Insects
- Small twigs
- Hair
- Other larger debris
Without the basket, debris can travel farther into the suction line or pump basket and potentially create a blockage.
Skimmer Weir
The skimmer weir is the small hinged flap or floating door located at the skimmer opening on many systems.
It performs several useful functions.
As water flows into the skimmer, the weir helps create stronger surface movement through the opening.
When the pump shuts off, the weir can also help prevent floating debris trapped inside the skimmer from drifting back into the pool.
A missing, broken or stuck weir can reduce the effectiveness of surface skimming.
Skimmer Lid
The lid covers the top access opening of the skimmer.
It allows the basket to be removed for cleaning while helping prevent people, pets or large debris from entering the skimmer opening from above.
Skimmer lids come in many different diameters, shapes and locking styles.
Faceplate
Some skimmers, especially those used on vinyl-liner or above-ground pools, use a visible faceplate around the opening.
The faceplate secures the liner or wall material around the skimmer opening and works with gaskets to create a watertight seal.
Gaskets
Skimmer gaskets help seal the skimmer body and faceplate against the pool wall or liner.
A damaged, improperly installed or deteriorated gasket can allow water to leak around the skimmer opening.
Vacuum Plate or Skim-Vac
Some skimmers use a removable vacuum plate that sits over the skimmer basket.
This allows a suction-side vacuum hose to connect through the skimmer while the basket remains in place to catch debris.
The correct vacuum plate must match the specific skimmer design.
How Does a Pool Skimmer Actually Work?
The pool circulation pump creates suction within the plumbing system.
That suction pulls water through the skimmer opening.
As water moves toward the skimmer, floating debris near the surface is carried with it.
The water then passes through the skimmer basket, where larger debris is trapped.
After leaving the skimmer, the water travels through the suction plumbing to the pump.
From there, it normally moves through the filter and any additional installed equipment before returning to the pool through the return jets.
This happens continuously whenever the circulation system is operating.
What Does the Skimmer Weir Door Do?
The weir door may look like a minor part, but it can significantly improve skimmer performance.
The partially restricted opening helps concentrate water movement near the surface.
This encourages floating debris to move into the skimmer.
When the pump stops, the weir typically floats upward and helps retain debris inside the skimmer housing.
If the weir is:
- Missing
- Broken
- Stuck open
- Stuck closed
- Installed incorrectly
surface skimming may become less effective.
Why the Skimmer Basket Is So Important
The skimmer basket protects equipment farther downstream.
Without it, leaves and other large material could travel into the suction plumbing or pump.
This can contribute to:
- Clogged plumbing
- Reduced water flow
- Pump basket blockages
- Loss of pump prime
- Reduced circulation
A cracked or broken basket should therefore be replaced rather than ignored.
Small cracks can quickly become larger when the basket is repeatedly exposed to water flow, debris and chemical-treated water.
How Often Should the Skimmer Basket Be Emptied?
There is no single schedule that works for every pool.
During periods of light debris, checking the basket once or twice per week may be sufficient.
During windy weather, storms or heavy leaf fall, the basket may need to be checked daily or even more frequently.
Never allow the basket to become completely packed with debris.
A heavily clogged basket can restrict water flow to the pump.
Can a Clogged Skimmer Damage the Pump?
A severely restricted skimmer can contribute to pump problems.
If the pump cannot receive enough water, it may begin pulling air or operating with inadequate water flow.
Symptoms can include:
- Air bubbles in the pump basket
- Reduced return flow
- Difficulty maintaining prime
- Unusual pump noise
- Weak skimmer suction
Keeping the basket clear is one of the simplest ways to help maintain proper circulation.
How High Should the Pool Water Be on the Skimmer?
Water level has a major effect on skimmer performance.
In many pools, the normal operating water level is approximately near the middle of the skimmer opening, although the exact recommended level can vary by skimmer and pool design.
If the water becomes too low, the skimmer may begin pulling air into the plumbing system.
If the water is too high, surface skimming can become less effective because water is no longer being concentrated through the intended portion of the skimmer opening.
Always follow the pool manufacturer's recommended operating water level when available.
Why Is My Skimmer Suction Weak?
Weak skimmer suction can have several possible causes.
Common possibilities include:
- A full skimmer basket
- A dirty pump basket
- A dirty filter
- Improper valve positioning
- Low pool water level
- A clogged suction line
- Air entering the plumbing system
- A pump problem
Weak suction does not automatically mean the skimmer itself needs to be replaced.
Start with the simplest maintenance items before assuming there is a larger plumbing or equipment problem.
What Is the Difference Between a Skimmer and a Main Drain?
The skimmer and main drain are both part of the suction side of many swimming pool circulation systems, but they draw water from different areas.
The skimmer primarily pulls water from near the surface.
A main drain or low suction outlet pulls water from a lower portion of the pool.
Depending on the plumbing configuration, valves may be used to control how much water is drawn from each suction source.
The skimmer is particularly valuable because many contaminants float before they eventually sink.
Can a Pool Have More Than One Skimmer?
Yes.
Larger pools commonly use multiple skimmers.
The number and location depend on factors such as:
- Pool size
- Pool shape
- Circulation design
- Return-jet placement
- Prevailing wind direction
Proper placement helps move floating debris toward one or more skimmer openings.
How Are Spa Skimmers Different?
Hot tubs and spas may use skimmer systems that look quite different from traditional swimming pool skimmers.
Many spas combine the skimming function with the filter compartment.
Water may enter through a floating weir, skimmer opening or filter housing and then pass directly through one or more cartridge filters.
Common spa skimmer configurations can include:
- Floating weirs
- Telescoping weir assemblies
- Filter baskets
- Integrated filter/skimmer housings
- Removable skimmer doors
Because spa designs vary considerably between manufacturers, replacement skimmer components should be matched carefully.
Do All Skimmer Baskets Fit the Same?
No.
Skimmer baskets may look very similar while having important differences in:
- Top diameter
- Bottom diameter
- Overall height
- Handle design
- Rim shape
- Locking tabs
- Manufacturer-specific features
A basket that is slightly too large may not sit correctly.
A basket that is too small may allow debris to bypass it or become difficult to remove.
Whenever possible, identify the skimmer manufacturer and model before ordering replacement parts.
Do All Skimmer Lids Fit the Same?
No.
Skimmer lids are available in numerous sizes and attachment styles.
Some simply rest in place while others twist, lock or use tabs.
Diameter alone may not be enough to identify the correct replacement.
The underside of the original lid, the skimmer housing and any visible part numbers can provide valuable identification information.
How to Identify an Unknown Skimmer
Older pools frequently have skimmers with missing labels or obsolete model numbers.
If the manufacturer is unknown, look for identifying information on:
- The underside of the lid
- The skimmer basket
- The weir door
- The faceplate
- Inside the skimmer housing
- Vacuum plates or accessories
Part numbers molded into plastic components can often provide the quickest identification.
Measurements can also be helpful.
For baskets and lids, measure carefully rather than estimating by appearance.
What Are Signs That Skimmer Parts Need Replacement?
Common replacement indicators include:
- A cracked skimmer basket
- A missing basket handle
- A broken or missing weir
- A lid that no longer fits securely
- A cracked faceplate
- Deteriorated gaskets
- A damaged vacuum plate
- Visible cracks in the skimmer housing
Replacing small components early can sometimes prevent larger circulation or leak problems.
Can a Skimmer Leak?
Yes.
Potential leak areas can include:
- The skimmer faceplate
- Faceplate gaskets
- The skimmer body
- Plumbing connections
- Cracks around the skimmer opening
A pool that consistently loses water until the level reaches the bottom of the skimmer opening may warrant inspection of the skimmer area, although other leak sources are also possible.
A separate leak-diagnosis process is usually required to determine the exact cause.
Simple Skimmer Maintenance
Routine maintenance can prevent many common skimmer problems.
A basic inspection should include:
- Emptying the basket regularly
- Checking the basket for cracks
- Making sure the weir moves freely
- Keeping the skimmer opening clear
- Checking the lid for damage
- Maintaining the proper water level
- Watching for air entering the system
- Inspecting visible gaskets and faceplates
These simple checks take only a few minutes and can help identify problems before circulation is significantly affected.
Common Pool Skimmer Problems
Some of the most common skimmer-related problems include:
- Basket constantly filling with debris
- Weak or no suction
- Stuck weir door
- Broken basket
- Water level too low
- Water level too high
- Air entering the suction system
- Leaking faceplate or gasket
- Cracked skimmer housing
- Incorrect replacement parts
Many of these issues can be corrected with relatively inexpensive replacement parts rather than replacing the complete skimmer assembly.
Do Not Run the Pool Without a Skimmer Basket
Running the circulation system without the skimmer basket may allow large debris to enter the suction plumbing.
Even if the pump has its own basket, allowing debris to travel through the underground or concealed plumbing unnecessarily increases the possibility of a blockage.
If a skimmer basket is cracked or missing, replacing it promptly is a simple way to protect the rest of the system.
The Bottom Line
A pool or spa skimmer may be a relatively simple component, but it plays an important role in circulation, filtration and debris removal.
It continually pulls surface water into the circulation system while the basket captures larger debris before that material can reach the pump.
Components such as the skimmer basket, weir, lid, faceplate and gaskets all contribute to proper operation.
Regularly emptying the basket, maintaining the correct water level and inspecting the skimmer for damaged components can prevent many common circulation problems.
And when a replacement part is needed, proper identification matters.
Skimmer baskets, weirs, lids and other components can look very similar but differ significantly in size and design.
Need help identifying a pool or spa skimmer part? Bath & Spa Parts Online carries skimmer baskets, weirs, lids, faceplates, gaskets, vacuum plates and other replacement skimmer components. If you are unsure which part fits your skimmer, contact us with the manufacturer, model, part numbers, measurements or photos and we can help identify the correct replacement.