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What Is A Pool Skimmer Weir?

Note: This post may contain affiliate links. This means that at no cost to you, we may receive a small commission for made purchases.

A lot of bodies of water contain a weir to help control their flow. For example, rivers have weirs that take the form of a barrier. Swimming pools are no exception to this having a barrier as a section of the skimmer which is used to filter and keep the water clean.

These barrier weirs float, so they can match the surface of the water to more effectively filter the water when installed in a spa or swimming pool.

These barrier-style weirs are not the only style of weir used in these pools, for example, you can get a barrel-shaped bobbing weir that has an attached skimmer basket. These work similarly to the barrier style weir but have their own advantages and disadvantages.

How Does A Pool’s Plumbing System Work?

If you are fully aware of the inner workings of a pool’s plumbing system (see also ‘Pool Plumbing Diagram & Layout Schematic Examples‘), you are better prepared to understand how a pool skimmer weir functions and what problems it is able to solve.

In terms of a pool, the water will generally come into the pool through the skimmer, or through a primary drain, or through both of these. After the water moves through these it will go into a three-port valve before going into a pump that is powered by a motor, this will then propel the water to travel through a filtration system to help keep it clean.

Once the water has been filtered through this part of the system it will usually be heated by either a heater or by solar energy depending on the system installed. After the heating, the water will go back into the pool via the valves.

While it seems like quite a lot, each of these stages is massively important to keep the water quality of a pool sufficient for people to be swimming in.

What Is The Specific Function Of The Skimmer?

So how does the skimmer part of the system work specifically? Many pools, especially larger ones with more water that needs cleaning, will install multiple skimmers to make sure the process is carried out as efficiently as possible.

These skimmers will collect specifically the water from the surface and will entrap any debris which should not be in the pool like; trash leaves, dirt, oil, and anything else that should not be there.

Skimmers also give access to the suction line of a pool which is usually utilized when the pool will need vacuuming.

The main aim of the function of the skimmer is to get as much debris collected before it can sink to the bottom of the pool where it will be significantly harder to reach and deal with automatically. If it does reach this point, pools with fewer cleaning systems in place will need human intervention.

As previously mentioned a lot of pools will have two or even more skimmers to help gather as much debris from the water’s surface.

Generally speaking, the skimmer is attached to the pump of the pool and will usually be built into the pool, but as references, there are free-floating skimmers that work better at getting water closer to the middle of the pool.

The material most of these skimmers are made from is plastic as it is durable enough, will not be worn down by the water, and is waterproof, it also helps the free-floating skimmers to float.

However, there are some older skimmers that are made from concrete. It is recommended to have at least 1 skimmer for every 500 square feet (46.45 square meters) of water.

Newer pool skimmers can even be robotic and have automatic systems included to make them function more efficiently. Some of these are even powered by solar energy similar to how some pools are heated with this same energy.

How Does The Weir Function With The Skimmer?

The skimmer (or skimmers) will generally appear as a tank with a pipe coming from the top. On this topside will be the weir which functions to regulate what amount of water enters the skimmer.

This is done by the weir to ensure that only a thin layer of the water will run through. This is to prioritize the velocity of the water over the amount of water used to make sure the water is sufficiently skimmed.

Pools are also designed with an equalizer line that will go from the underside of the skimmer and extend to around 12-18 inches, this will then go through the wall of the pool and enter the water.

When choosing where to install a skimmer (see also ‘Steps For Installing A Thru Wall Skimmer On An Intex Pool‘)  in a pool, going in a downwind direction makes it, so the wind will help in making the water and its debris move into the skimmer.

If the water runs above the weir, this is when debris enters the skimmer eventually making the weir move lower as more water enters. When this is done suction will stop and eventually the weir will rise again and suction will continue, this is done to ensure that debris does not get released back into the pool.

This is how most weirs function, but the floating barrel-style will instead collect large debris in their basket to be manually removed.

How To Replace The Skimmer Weir For A Pool?

Luckily for pool owners, weirs are actually relatively easy to replace. For a built-in weir, usually, the process will just consist of using pliers to remove the old or either damaged weir and then installing the new weir that will match the size specifications.

After this, the next steps will be different depending on the brand of weir used, but sometimes safety pins will be removed, or retaining rods will be released.


So now you know what a pool skimmer weir is! This device is paramount for keeping a swimming pool or spa having clean water to make the enjoyment of swimming in these pools as hygienic and safe as possible. Make sure to check filters regularly and only use them for as long as the manufacturer recommends.

author avatar
Anthony Barnes
Anthony Barnes is the founder of Water Heater Hub and a second-generation plumber by profession. Before developing Water Heater Hub, Anthony Barnes was a full-time plumber, and he has undertaken a wide variety of projects over the decades. As a second-generation plumber, it was easy for Anthony to get used to the technicalities of all from a tender age


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