Pool Skimmer Box

A Skimmer box, usually made from plastic and cylindrical in shape, is in most cases installed on the sidewall at the waterline. It is connected to the pool pump via plastic pipework so its main function in the pool is to filtrate and capture the larger debris such as leaves before it reaches the pump.

In the skimmer box, there is a plastic basket in which the debris is captured and this has to be periodically emptied, depending on how often it fills up and what kind of waste it captures. This is an important part of any pool maintenance program

The function of a skimmer basket is critical for a number of reasons

1. It prevents larger debris from reaching the pool pump and potentially damaging the pool equipment
2. It prevents large objects from entering the suction line of the pipework, such as children’s toys, thereby causing a pipe blockage which is every pool owner and pool contractor’s worst nightmare as the blockage is often difficult to locate and often requires a lot of excavation to remove the blockage.

It is vital that the basket be emptied on a regular basis for a number of reasons. If leaf waste or other garden waste is left in the skimmer basket, as it breaks down it releases phosphates into the water which will affect your pool chemistry and cause the water to turn green

Skimmer boxes are made for different kinds of Pools such as

1. Concrete Pools
2. Fiberglass Pools
3. Molded skimmer box for fiberglass pools
4. Spa’s

Concrete Pool Skimmer Box

A skimmer box for a Concrete Pool is installed by encapsulating it in concrete and securing it to the Pool using a metal rebar to prevent movement and to hold the skimmer box into place. So you can imagine if your old skimmer needs replacing it can be quite a mission to remove the old and in with the new unit. Due to the removal process is so labor-intensive the replacement cost can be quite high with waterline tiles and pool bull nosing (coping) having to be removed and re-installed as part of the process. In many cases, old tiles break and they are 25 years old, matching them can be very challenging

So if a concrete pool is so securely installed why do they crack or fail..?

There are a few reasons for this, namely concrete will continue to grow and expand over many years so after a long period of time the concrete will begin to place pressure on the plastic skimmer box. Evidence of this can be seen if you stand over the skimmer and look at the shape of the box which will often contort to an oblong type look, causing cracking.

Not removing the basket can also cause damage as the basket often gets sucked deeper into its seat making its removal very challenging. It is very important in this instance not to use a sharp object to try and remove the basket

Fibreglass Pool Skimmer Box

Most all Fibreglass Pools that have been manufactured in the last 20 years will have a stand-alone skimmer box that is bolted to the side of the pool and sealed with a silicone product. There is a faceplate installed at the end to hide the bolts, for aesthetic reasons.

Unlike a concrete pool skimmer box, it is not encapsulated in concrete. It is free-standing below the ground and merely secured by the bolts. The main reason a fiberglass pool skimmer box in Perth will fail is due to sand shifting around the box. In time the sand around the skimmer box will shift and contract to cause downward pressure on the pipework that is attached to the skimmer box. As this downward pressure increases, it will either cause a crack at the bottom of the skimmer or pull the skimmer away from the mounting or crack the facia of the skimmer

The silicone seal can also perish after a long period of time due to exposure to abrasive chemicals such as chlorine, salt, or acid.

Regular maintenance such as the emptying of the basket will always prolong the life of the skimmer box.

With the increasing popularity of poured concrete around a pool, it is crucial that your contractor allows for movement and places expansion joints around the skimmer box, whether it’s for a fiberglass or concrete pool.

Moulded Skimmer Box for a Fibreglass Pool

Many Fibreglass Pools manufactured in the 70s and 80s came out with a molded skimmer box which means it formed part of the entire pool structure. This is a completely floored method and has thankfully been replaced by the bolt on skimmer box.

At the base of the skimmer, there is a plastic fitting which is normally secured with silicone on the inside of the skimmer. the plastic fitting generally has a thread and is secured on the outer by a large plastic lug, the pipework then being installed into the fitting.

In the early days, a metal fitting was used which only compounded the problems with this style of the skimmer, to another level.

Silicone as you know breaks down over time and that, along with sand shifting and corrosion of the plastic, eventually causes the skimmer to fail, rendering the pool filtration and cleaning faulty.

Another particular problem with the style of skimmer is, that you cant properly attach a pool cleaner because there is no way to attach a vacuum plate that the hose goes into. That is why you always have to be creative and use bricks to hold the vacuum plate down or other such creative apparatus.

Because the skimmer is part of the pool structure and therefore fiberglass in construction, it is prone to osmosis and blistering over a long period of time and this can cause water loss if not repaired.

So how can this molded skimmer be replaced or fixed you might ask.?

When we are restoring an old fiberglass pool it is often easy to close it and cut a hole into the pool shell and install a standard skimmer. This process can be challenging if you’re not renovating due to the invasive nature of the installation.

Some ideas to maintain a healthy skimmer box

1. Clean out the basket regularly and don’t use a metallic object if your basket is tight or jammed, seek advice.
2. If you are renovating around your pool always insist your contractor leaves expansion joints to prevent future problems
3. If you have a molded skimmer box and you are having to use bricks to hold down the vacuum plate, cover them in cloth to prevent damage to the pool or vacuum plate, as this can affect the suction, therefore, affecting your pool chemistry

I hope in some way I have helped you to either identify or prevent future problems with your skimmer box which can be most costly if repairs or replacement is required. If you have any questions there will be a link to a contact form where you can send any queries