Most of what falls in your pool floats for a while before it sinks. Leaves, pollen, bugs, sunscreen, and hair all sit on the surface first.
The skimmer grabs them during that window. Miss the window and all of it drops to the floor, where it stains, feeds algae, and has to be vacuumed instead.
Where it sits in the system
Your pump pulls water from two places, the skimmer and the main drain at the bottom. The skimmer is the square opening cut into the pool wall at the waterline.
Water runs from the skimmer to the pump, then through the filter. If you have a heater or a salt cell, it passes those next. Then it comes back through the return jets.
So the skimmer is the front door. Everything downstream depends on it working.
What is inside it
Open the lid on the deck and you are looking at four parts.
- The weir, the hinged flap in the opening. It floats up and down with the water and creates a thin fast layer that pulls debris in. It also keeps the debris from washing back out when the pump stops.
- The basket, which catches everything before it reaches the pump.
- The throat, the opening at the bottom leading to the pump line.
- The equalizer line, a second port that lets the skimmer pull from the pool if the level drops too far. Not every pool has one.
Some skimmers also hold a float valve that shuts the line off when water gets too low.
The water level is the whole game
A skimmer only works in a narrow band. The water should sit around the middle of the skimmer opening, roughly halfway up the mouth.
Too low and the weir cannot float. The skimmer gulps air, the pump loses prime, and the shaft seal starts cooking.
Too high and the water runs over the weir instead of under it. Debris drifts past the opening and never gets caught.
This is why the level drops after a backwash and why refilling matters, which we cover in how to backwash a pool filter.
Empty the basket before it fills
Check it weekly. Once a week is the minimum during leaf season here.
A packed basket starves the pump. The motor works harder, the flow drops, and the filter stops getting enough water to do its job. Owners often blame the pump for what is really a full basket.
Pull the basket out rather than reaching in with your hand. Rinse it and look at it. Cracks and missing chunks mean debris is getting past into the pump basket and eventually the impeller.
Things that go wrong
A skimmer is simple, so there are only a few failures worth knowing.
A missing or broken weir is the most common. Without it the skimmer still pulls water, but far less effectively, and debris washes back out every time the pump cycles off. Weirs are cheap and clip in.
A cracked skimmer body is the expensive one. Ground movement and freeze damage both do it, and the crack leaks water straight into the soil. If your pool loses water down to the skimmer mouth and then stops, that is the first place to look. Our guide on finding a pool leak shows how to confirm it.
A clogged throat is usually a stick or a wad of leaves jammed below the basket. Flow drops, the pump strains, and the pressure readings go strange.
Get more out of it
Point one return jet slightly toward the skimmer. The current carries surface debris to the opening instead of letting it settle in a corner.
Run the pump during the day, when people swim and the wind blows things in. That ties into how long to run your pool pump.
Use a skimmer sock over the basket during pollen season. It catches the fine stuff before it reaches the filter and buys you weeks between cleanings.
Skimming by hand still helps. A tech does it on every visit, and our list of what a weekly service includes starts there.
Need a weir, a basket, or a lid? We stock them at the supply store. Call (361) 575-5821.
Frequently Asked Questions
What does a pool skimmer do?
It pulls water off the top of the pool and catches floating debris in a basket before that debris sinks. The water then continues to the pump and the filter.
Where should the water level be for the skimmer to work?
About halfway up the skimmer opening. Too low and the skimmer pulls air and the pump loses prime. Too high and water flows over the weir flap instead of under it, so debris drifts past.
How often should I empty the skimmer basket?
At least once a week, and more often during leaf or pollen season. A full basket cuts the flow to the pump and makes the whole system work harder.
What is the flap in my pool skimmer called?
The weir. It floats with the water line and speeds up the thin top layer so debris gets pulled in. It also stops debris from washing back out when the pump shuts off.
Why is my skimmer not pulling water?
Usually a low pool water level, a packed basket, or something jammed in the throat below the basket. A closed skimmer valve at the equipment pad will do it too.
Can a pool skimmer leak?
Yes. The seam where the skimmer meets the pool wall is a common leak point, and freeze or ground movement can crack the body. If your water drops to the skimmer mouth and then holds, that is the likely spot.
