Skimmers

Use the right type of skimmers for your type of pool. Gunite/plaster, vinyl liner, fiberglass, above ground liner, steel walled liner, each require a specific type of skimmer with any gaskets for the proper installation. There are many models of skimmers available and the correct ones should be used for your type of pool.

A skimmer consists of the following components:

An access cover on the deck to get into the skimmer
Floating weir door
Strainer basket
Suction line to the pump
Optional equalizer line or to main drain

A skimmer should have a strainer basket to capture large debris and prevent debris from getting stuck in the pipes. There are weighted skimmer baskets to prevent them from floating. Some folks put a rock in the skimmer basket to prevent floating. Be careful using a rock as folks have accidentally dropped the rock into the skimmer and down the pipe.

Skimmer Covers

Most skimmers come with a plastic round or square cover or you can add decorative covers that can blend in with the deck can be used. Planning and installation of decorative covers needs to be done during the pool build. Most cannot be easily retrofitted to an existing pool.

Pour-A-Lid

There are decorative skimmer covers like Pour-A-Lid. The Pouralid’s are more for poured surfaces but folks have cut stone to fit them. It takes a good mason to fit a stone in the lid.

Hide Skimmer Cover

Hide Cover is a 12″ square cover is used to cover skimmer box openings and any external inspection points around your landscape. Each cover is available in a range of depths. Make sure the proper depth kit is ordered for the materials you will be using in it.

Brass Skimmer Cover

Brass covers come with bonding wires attached. Brass skimmer covers are metal and brass is a great conductor.^[1] They have to be connected to the bonding grid. If you didn't take this into account when you constructed the deck there is a problem.

Some possible solutions are that IF you water is bonded by a waterbug in the skimmer then you just attach to that. That is only a half solution to the problem if you have two skimmers. depending on how much work you want to go to and how your deck is set up, drill under the deck and fish a wire through. This can be a large amount of work and can be very frustrating.

Skimmer Weir Doors

A weir door is a part of a swimming pool skimmer that helps to control the flow of water through the skimmer. The weir door is typically located near the top of the skimmer and is attached to a hinge or pivot. The weir door is an important part of a pool's filtration system and helps to keep the water clean and clear.

Skimmers need a weir door to do their skimming function.

The weir door should swing freely with the water level anywhere along the skimmer mouth. The top of the weir door should follow the water level. The weir door should not move toward the pool itself. There should be a stop that prevents it from moving toward the pool.

The weir door should just be pushed back a bit as the water flows over the lip of the door into the skimmer. Debris should be following that water flow over the lip into the skimmer and the closed weir door keeps the debris from returning to the pool.

A skimmer will draw in water just fine without a weir door, but it won't skim debris off the surface any where near as well.

The door is to increase the amount of water taken from the top of the water where the floating debris are. Without the door on, most of the water is taken to the filter from beneath the surface and would leave a lot of the floating stuff on your water.

The skimmer weir limits the flow coming in to maybe the top 1/2" of water.^[2] If the cross section area of the skimmer throat is 3"X12", that's .25 sq ft. Let's say the skimmer is pulling a measly 10 gallons per minute. That's 1.3 cubic feet per minute. That means the flow coming through the skimmer throat will have a velocity of 5.2 ft/minute or .087 feet per second to maintain the water level. Now reduce that opening to 1/2"X 12". That's 1/6 the area so to maintain the water level - and water will seek its own level - that water is moving six times as fast or 5.2 feet per second. That's a pretty good clip - 3.5 miles per hour - enough to overcome slight breezes and currents and pull water into the opening. Unless you have a return jet pointing straight at the skimmer throat, any surface debris being shoved along by the return flow will just go right on past the skimmer otherwise.

How to Replace a Missing Skimmer Weir Door

If you are missing the weir door the first step is to try and identify the model skimmer you have. Look for part numbers molded in the bottom of the skimmer lid or the skimmer basket and do a search on the number.

There are replacement weir doors with spring loaded pins they swing on.

You may want to get a weir door a bit narrower then what you had. For example, for a Pentair Swimquip U3 Skimmer you would be better off getting the 8" spring-loaded weir as opposed to the 8 3/8" that usually is installed. It is less likely to get jammed and works just as well. Many times, on a pool that age, the skimmer throat is no longer square, but slightly mis-shappen and the "proper" size causes problems.^[3]

Difficulty with Replacement of Weir Doors on Pentair Skimmers

Universal weirs have spring-loaded posts that grip the walls of the skimmer box, while the original Pentair weir is secured with a single stainless screw. The Pentair weir has a permanently fitted and pre-drilled hinge piece attached to the floating blade of the weir. The hinge piece fits into a slot on the floor of the skimmer box intake. The slot part consists of a rear wall and two tabs. The hinge part of the weir slips into this slot and is secured by the screw.^[4]

It is very difficult for one person to slip the hinge piece into the slot, hold the weir to keep it from floating out, locate the screw hole right on the skimmer floor, insert the screw, and tighten it. Either a small Phillips head Z screwdriver or a regular Phillips screwdriver with a long shaft is required to tighten the screw. It could possibly be a two-man/woman job with one person in the pool holding the weir in place while the other person inserts the screw and tightens it. It's not a great design.

Once installed it works better than the preceding universal friction-fitted weirs and it won't be floating out. However, be prepared for a frustrating installation.

Venturi Skimmers

Venturi skimmers include a return line with a venturi to increase the skimming action. Some people say it is a gimmick and not worth it. The diagram below illustrates how theoretically a venturi skimmer should work.

One member reported on how he observed the venturi skimmer working.^[5] With water being returned to the venturi in the bottom of the skimmer, the pump runs at a lower RPM and gets the same skimming action as when the venturi return line is turned off and the pump rpm is increased. So you basically get the same skimming for less cost/electricity.

The picture below shows a venturi skimmer on the left being installed next to a large leaf collector on the right.

Skimmer Crack Repairs

Skimmer cracks are generally the result of settling/movement around and underneath. Ideally it's best to dig up the area, replace any bad items, and re-pack to prevent further movement. It can be worthwhile trying to fix a skimmer crack with epoxy and seeing if it holds.

Repair products members have used include^[6]:

The only true fix is a skimmer replacement. Most pool-leak detection companies are able to do that with minimal damage to the deck.

Why Are There Two Holes in The Bottom of my Skimmer?

When you look in the bottom of many skimmers you see two holes. Those skimmers are manufactured with pipe connections on the bottom for two lines. One line will run to the pump suction. The other line may or may not be used.

If the second pipe is not used then you will see a white plug with a raised square screwed into the hole. If the hole is open then the main drain on the bottom of the pool is probably connected to it.

Are Main Drains Connected to the Skimmer?

In most old pools the main drain was tied into the bottom of the skimmer. For the main drain to work at all you needed a floating diverter valve (or some type of device inside the skimmer to turn on the main drain).

In most newer pools, the main drain(s) are plumbed back to the equipment pad with a valve to shut off or control the amount of flow. The skimmer(s) are also individually plumbed back to the equipment with associated valve(s).

The hole that is away from the water is normally the one that is plumbed back to the equipment pad.

The hole that is next to the water is normally connected to the main drain.

When the main drain(s) are plumbed back to the equipment pad, the skimmer hole closest to the water is normally plugged.

What is a Skimmer Float Valve?

When a skimmer is connected using both bottom holes to the pump suction and to a main drain or equalizer line a float valve (also called a diverter) is necessary over the holes to cause water flow from the main drain/equalizer pipe into the pump suction. Without the float valve the main drain/equalizer cannot operate.

A skimmer may use a round float valve or an oval float valve. They are not interchangeable and a skimmer will use one type or the other.

When there is water in the skimmer from the pool the float valve "floats" above the holes and the pump pulls water in from the skimmer basket.

If the skimmer water level drops the float valve drops down on the two holes and creates a seal that should cause the pump suction to then pull water from the other hole. This ensures the pool pump does not run dry when the pool water level and thus skimmer water level drops.

Float valves never work well and modern pools rarely use them. It is better to plumb the skimmer suction line and the main drain line to the equipment pad and combine them using a 3-way diverter valve.

How to Adjust Pool Skimmer Suction

In normal operation you should see little or no water movement if you look down at the water in the skimmer. You should not see a vortex or waterfall of water flowing through your skimmer. If you do then check that the water level is at least halfway up the skimmer mouth and the weir door is swinging freely.

If you vacuum the pool through the skimmer or use a vacuum powered pool cleaner you may want to increase pool suction. Some things to try are:

Check that the skimmer basket is clean and has no leaves or debris in it
If you have a Variable Speed pump you can increase the pump RPMs
You may have one or more valves in front of your pump that can be adjusted to increase skimmer suction
If you have a valve to balance main drain suction and skimmer suction it is best to run the skimmer 100% open the main drain about 10% open.

For more help with your pool equipment start a thread in the TFP Forum and you will get personalized help.

What To Do If You Are Missing Your Skimmer Basket

Your skimmer basket is necessary to help keep larger debris out of your filter. Its easier to clean out a basket then it is to clean a filter. And if you use skimmer socks which go inside the basket you also collect very fine dust and schmutz.

You need to measure the diameter of the little lip that the basket will sit on and the depth between the lip and the bottom of the skimmer. Take that info to your local pool store and see which basket will fit the best. If there is any info on the skimmer lid about the manufacturer of the skimmer, take that with you also.

Skimmer Basket Pops Up When Pump Turns Off

A quick fix is to use a weighted skimmer basket or put a rock in the basket to hold it down. The picture below is of a weighted skimmer basket and you can see the weight in the middle of the bottom.

Use a rock that is too large to get into the pipe. You don't want to drop the rock accidentally one day and have it end up jamming inside the pipe where you can't get at it to remove it.

It is normal for there to be a little tiny bit of backflow when the pump shuts off. It will be very small, but often enough to move the basket. The filter is presurized and that pressure will go out the intake if the pump isn't preventing it.^[7]

You may have this problem if you use skimmer socks. A skimmer sock is just enough to float the skimmer basket. A rock fixes it.

Another reason is air in the filter. Air is compressible and decompresses when the pump turns off. An oversize pump or and undersized filter can also cause problems. Use the air relief valve on your filter to remove air from the filter. ^[8]

What Are Skimmer Socks and Should You Use Them?

Skimmer socks are cloth put over the skimmer basket that acts as a prefilter and catches small debris before it is sucked through the pump to your filter. Folks who use skimmer socks feel the skimmer socks are easier to keep clean than their filters. It doesn't work for everyone.

So much of what is filtered in your pool is minute small schmutz like pollen. If you catch it before it gets to the filter, you save the filter from excess dirtying and required backwashing to clear it out. Some members feel it is easier to replace a hairnet once a week than have to wash out your cartridge filter every few months. Cleaning out the stuff that gets caught in the tiny holes of the skimmer basket can be a huge pain. Much easier to just grab the hairnet full of stuff and chuck it and have a perfectly clean basket than trying to hose that thing out.

Also those with pine tree needles know how they can slip through the small slots of the skimmer basket, so we're protecting the pump from them or from potential clogs in our pipes.

If you have dogs who swim in your pool then swimmer socks can catch the dog hair before it clogs your filter.

Other members let the filter do its job. It is an individual choice really but skimmers collect a lot of stuff. Lots of leaves, beetles, etc. If it makes it through the holes in the skimmer basket, it is welcome to visit the filter until it gets cleaned out. They prefer to quickly empty the filter basket over the fence rather than have the disgusting mess of cleaning filter socks/hairnets!

One member discovered discovered the skimmer sock was completely clogged with crud, and the skimmer basket had busted it's seams around the bottom and sides!^[9]

If you use skimmer socks you need to check them often. Maybe once a day. A warning about skimmer socks. If there is a lot of pollen in the air, check often, once they get truly coated in pollen snot they can stop water flow.

Skimmer sock products include:

Home Depot one gallon paint strainer netting products. They are cheap, reusable, and can be pulled out of the skimmer, flip it inside out to dump bugs and junk, then beat it against the fence to remove fine debris. Then it goes back in. They catch most of the bugs and dog hair while allowing water to flow through quite well. ^[10]
Hairnets are extremely cheap and no cleaning involved, you just throw them away.
3M Disposable Hair Net 407, Universal Size
Impresa Products 20-Pack of Pool Skimmer Socks
12 Pool Skimmer Socks Filters and Baskets

Note that the skimmer sock goes on the INSIDE of the skimmer basket, not the OUTSIDE.^[11] Members who put the skimmer sock on the outside of the basket has found it sucked into the pump.

One member reported the skimmer sock was completely clogged with crud, and the skimmer basket had busted it's seams around the bottom and sides. This was on an above ground pool with a large pump that created a lot of suction.^[12] This was on an above ground pool with a large pump created a lot of suction.

Another member was adding borax one night via my skimmer, and didn't take the sock off of his skimmer basket beforehand.^[13] Being in a hurry, he dumped a little too much borax at one time in the skimmer, heard the pump bog down, heard a crack, and found out that the top lip of my skimmer basket had separated from the rest of the basket. Sadly, this wasn't the first time he did this.

Bottom line - if you've got a lot of stuff in the pool, or a lot of stuff getting blown into the pool, check your skimmer sock frequently, or take it off if you can't check it frequently.

Skimmers for An Above Ground Pool

Many above ground pools do not come with skimmers. They come from the manufacturer with one or more round holes in the side of the liner which connect a hose to the pump suction. With this type of suction system on an above ground pool debris, such as leaves and insects, from the surface of the pool water is not automatically cleaned as the pump runs.

Intex Skimmer Install shows how a skimmer is installed. Make sure you buy a skimmer for an above ground pool like the Hayward SP1091LX. A skimmer for an above ground pool comes with gaskets to seal the hole you will be cutting in the liner.

Should You Put Chlorine Tablets in the Skimmer Basket?

The problems with Trichlor tablets are primarily when the pump is not running. For tablets in a skimmer, when the pump is off they continue to slowly dissolve and if the local acidity gets to the copper in the heat exchanger in the gas heater or to the pump seals, then there can be serious problems. We have quite a few reports of people with copper and associated stains in their pool from doing this so even if the copper pipes didn't get to the point of leaking they can still cause problems.^[14]

The advice not to put Trichlor tablets in the skimmer is simple and general. It's similar to advice for the amount of chlorine relative to CYA to prevent algae. Sure, some pools may be poor enough in algae nutrients to not need as high a chlorine level, but it's far simpler and safer to set the limit so that it works in thousands upon thousands of pools regardless of algae nutrient level. However, it's your pool and all we can do is provide information. If you keep the pump running until the tablets dissolve or if you remove them when the pump is off then you minimize the chance of damage.

If you want to use Trichlor tablets use a floating dispenser. Although tie the dispenser so it cannot get near any stainless steel in your pool.

Should You Put Stabilizer in the Skimmer Basket?

The instructions on most packages of stabilizer/CYA say to add it to the skimmer. This can cause the skimmer line to get clogged with the stabilizer as on this thread. If the stabilizer gets through your pipes it can clog your filter, reduce your water flow, and raise your filter pressure. The problems of undissolved stabilizer in your filter depends on your filter type - sand, cartridge, or DE.

Solid/granular CYA should be placed in a sock and the sock put in the skimmer basket or suspended in front of a pool return. If suspending near a return jet, ensure the sock cannot rest against the pool surface since the granules are acidic and could potentially discolor the surface. After adding CYA you should leave the pump running for 24 hours and not backwash/clean the filter for a week. After soaking for about 30 minutes, squeezing the sock periodically will help it to dissolve faster.^[15]

Should a Piece of Copper be put in a Skimmer to Control Algae?

Just dropping a copper pipe in the pool is not going to kill algae. There either needs to be some sort of mechanism that releases copper from its solid state and puts it into solution in the pool, such as electrical current in a copper ionizer, liquefied copper in copper algaecide, or super aggressive low pH water that destroys copper (and other things you don't want destroyed) in heat exchangers or old copper plumbing.^[16]

Copper in the water can cause unsightly stains that are difficult (sometimes impossible) to remove, which is why we never recommend the use of copper. While copper can help slow down algae growth, chlorine alone is sufficient if you maintain an appropriate Free Chlorine level. Simply putting a piece of solid copper in the skimmer does not give you any meaningful control over the copper level in the water.

For more read Copper in Pool Water

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Skimmers - Further Reading

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