Leaves are floating on the surface, the pump is running, and the skimmer is just sitting there. No pull at the opening, no little whirlpool, nothing. The weir door is stuck straight up like it’s saluting. If you’ve had a pool through one fall in Ventura County, you’ve probably seen some version of this, and it’s one of the more common things we sort out on our Camarillo pool service visits.

The pool skimmer looks like the least complicated thing in the yard: a plastic box with a basket and a flap. But it’s where most of your surface water gets pulled to the pump, and when it isn’t working, the pump, the filter and the water all notice.

How a pool skimmer is supposed to work

Water flows over the weir (the floating flap at the opening), through the basket, and down a pipe to the pump. Pentair’s installation guide for its Admiral S-15 skimmer describes it exactly that way. The weir rides up and down with the water so it skims a thin layer off the top, and it’s also what keeps leaves from drifting back out when the pump stops.

Many skimmers also have an equalizer line, a second pipe that lets the skimmer pull from below the surface if the water drops too low, so the pump doesn’t suck air. Not every pool has one, and local codes vary on whether they’re allowed.

Lost suction: the usual suspects, in order

When the skimmer stops pulling, check these before you assume anything is broken.

Water level. This is the big one in fall, after a hot, dry stretch of evaporation. Pentair’s manual says that when the water drops below the weir, the pump draws the skimmer down to the equalizer float. Waterway’s Renegade skimmer manual puts it more bluntly: when the level drops below the weir door, water no longer flows from the pool. Aim for the water to sit around the middle of the skimmer opening.

Basket. Pentair notes the same starving effect happens “if the basket is plugged with leaves and debris.” A basket full of sycamore leaves is effectively a closed valve.

Valve position. Many pads have a valve that splits suction between the skimmer and the main drain. If someone turned it to favor the drain, the skimmer gets almost nothing. Worth a look before you go digging in the line.

A clog in the line. If the basket’s empty and the water level is fine, something is likely stuck in the pipe below the basket. Tennis balls, pool toy parts and the occasional lizard all end up there, usually because the basket was cracked or missing and let them through.

Air at the pump. If the pump basket has bubbles and the pump sounds rough, the suction problem may be an air leak at the pump lid or a fitting. That’s a pump problem, and we covered it in our post on pool pump noises and leaks.

Stuck, broken or missing weirs

A weir that’s stuck in the up position blocks most of the opening and starves the skimmer. A weir that’s stuck down lets water flow but doesn’t trap anything, so leaves drift back out when the pump turns off. A missing weir does the same thing, permanently.

Waterway’s manual says to check the weir for free swing movement on a regular basis and to replace worn or damaged weirs. They wear out at the hinge pins and the float gets waterlogged. Honestly, a weir is one of the cheapest repairs on a pool, and a lot of people live with a broken one for years because they don’t know it’s a separate part.

Cracked baskets and lids

Baskets crack from age, sun and people standing on the lid to look in. A cracked basket still sort of works, but it lets debris through to the line and the pump basket, which is how lines get clogged in the first place.

Lids are a safety issue more than a performance one. Pentair’s manual says to keep the skimmer lid secured at all times and to replace it if it’s worn or damaged. A deck lid with a cracked edge is an ankle injury waiting for a barefoot kid. Swap it.

Cracks in the skimmer body or throat

This is the expensive one. The skimmer body is set into the concrete under the deck, and the throat is the opening that connects it to the pool wall. Ground movement and settling can crack the body itself or open a gap where the throat meets the plaster and tile.

Signs: a visible crack in the plastic inside the skimmer, a separation line around the throat, or tile at the skimmer that’s loose or cracked. A crack at the throat can also let water out of the pool, which shows up as a pool that keeps needing a top-off.

Small cracks at the throat can sometimes be sealed. A cracked skimmer body usually means cutting out the deck and coping around it to replace the skimmer, then patching the deck back. If you’re already planning work on the deck or tile, it’s worth folding the skimmer into that project; our post on what to replace first in a pool remodel walks through the order.

Pool skimmer problems and what they usually mean

Santa Ana winds and the fall skimmer problem

Fall is when skimmers earn their keep. Santa Ana winds blow leaves, dust and palm debris into Conejo Valley and Camarillo pools for days at a time, and oaks and sycamores drop leaves for weeks.

That’s when Pentair’s “once a day if it is especially windy” line matters. A skimmer that’s full by noon starves the pump all afternoon.

Skimmers on commercial pools

HOA, apartment and hotel pools run more water through each skimmer and get more debris, so the same problems show up faster. Commercial skimmers are rated for it: Waterway’s Renegade public pool skimmer lists a maximum flow of 75 GPM and says suction pipe velocity shouldn’t exceed 6 feet per second. Those numbers matter when someone upsizes a pump without checking whether the skimmers and pipes can handle the flow.

Waterway’s manual also points out that low water makes it harder for swimmers to climb out, not just harder on the pump. On a busy community pool, that alone is a reason to keep the level right.

Asked at the pad, every week

Can I run the pool without a skimmer basket? You can, but you shouldn’t. Everything the basket would have caught goes straight to the pump basket or into the line.

Is a skimmer sock worth it? For fine debris and pollen, a mesh sock over the basket helps. Just remember it clogs faster than the basket, so it needs emptying more often.

My skimmer gurgles. Is that bad? Gurgling usually means the water is low enough that the skimmer is pulling air. Top off the pool and see if it stops. If it doesn’t, check for an air leak at the pump.

Is a cracked skimmer an emergency? Usually not, unless a lid is broken in a way someone could step through. For what actually counts as urgent, see what qualifies as a pool emergency.

Skimmer acting up?

Send us a photo looking down into the skimmer with the basket out, one of the opening from the pool side, and one of your equipment pad. That’s usually enough to tell a weir swap from a deck job. Send the photos here and we’ll get back to you. Bigger repairs land under our pool repairs and upgrades work.

We service Pentair, Jandy, Zodiac, Hayward and Sta-Rite equipment across Ventura County. Call (805) 586-2055.