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Swimming Pool Anatomy

by Matt Giovanisci | Last Updated: July 28, 2013

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What is a swimming pool? When you boil it all down, a swimming pool is just a giant structure that holds a large amount of water. However, each swimming pool is different in its own special way.

Some pools are above ground and some are in-ground. They can have different surfaces like vinyl, tile, plaster or fiberglass. No matter which type of pool you have, they all do the same thing: provide entertainment and a means of cooling off.

City Water vs. Well Water

Depending on where you live and what type of water system you have, your water make-up can be vastly different. For instance, where I live, we have city water. City water is, of course, provided by your city or town. It’s plumbed directly to your house from a main water supply.

Well water comes from a well in the ground that resides on your property. The big difference between well and city water is that the chemical make-up of city water is controlled by a professional facility, and well water is controlled by you.

Well water tends to have more minerals, including copper and iron, which can be bad for your swimming pool. So, with well water, you may want to use a metal sequestrant If you click this link and make a purchase, we earn a commission at no additional cost to you. to avoid oxidation and staining on your pool walls and floor.

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Common Pool Water Contaminants

Since most swimming pools are located outside, and we all live on planet earth, we experience a lot of the same water contaminants in our pools. Some common ones include:

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An Inground Pool Anatomy

Here is a drawing of a basic in-ground pool set up. This illustrates the places where water comes in and out of your pool. Water is sucked in through the skimmer(s) and the main drain(s), pumped through your filter, and then back into your pool through the return lines.

inground-pool-anatomy

Note: This is not how EVERY in-ground pool is set up, but the logic works the same way. Every pool has a skimmer to suck in the water into and through the filter, and every pool has a return line to push the water back into the pool.

An Above Ground Pool Anatomy

An above ground pool usually only has one skimmer and one return jet. Water is sucked in through the skimmer (attached to the side of the pool with a basket for catching large debris) and pushed out through the return jet.

The water is pulled in through the front of your pump (which includes another basket for catching large debris), then pushed through your filter and back into your pool.

Above Ground Pool

The Suction-Side Of Your Pool

Skimmers

These are buckets, built into the concrete, that house a skimmer basket (hence the term, skimmer). Skimmers If you click this link and make a purchase, we earn a commission at no additional cost to you. are what suck the water out of the pool and through your filter system. They should have a small plastic basket inside to catch any large debris including leaves, sticks, and bugs before it enters your pump (which also has a basket).

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Main Drain

This is another place where water is sucked in and pushed through your filter. Main drains If you click this link and make a purchase, we earn a commission at no additional cost to you. are usually located at the bottom of the deep end of the pool. While the skimmers take care of pulling water off the top of the pool, main drains are great for pulling water off the bottom. That way, you are pulling water from all areas of the swimming pool.

Note: Older in-ground swimming pools probably won’t have two main drains. The reason why newer pools have two is for safety. When you have two, it splits the suction in case something or someone blocks one of the drains.

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The Pressure-Side Of Your Pool

Return Jets

This is the jet that pushes the water back into your swimming pool after it’s been filtered. The return jets If you click this link and make a purchase, we earn a commission at no additional cost to you. also help to push or circulate the water around, allowing the skimmers a better chance to pick up more debris.

Tip: If you have two or more return jets in your pool, angle some of them down towards the floor and in one direction, either left or right. You want to create a circular motion while helping to kick debris off the bottom with the jets angling down.

Note: If you have jets in your steps, these are also return lines.

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Your Filtration System

Your filter system should be made up of two parts, the pump and the filter. Often, owners will refer to these as one unit, but they are completely different. Your pump is what moves the water and the filter is what…well…filters it or cleans the water.

pool-filters-and-pumps

The Pump

This is the unit that draws in the water from the pool, pushes it through the filter and back into your pool. It consists of two parts. The pump, which technically is the bucket with a lid and a basket inside. There is also an impeller that spins super fast. That’s what sucks the water in and out.

The other part is the motor. The motor is the heavy long tube shape piece behind the bucket with the lid. Its job is to spin that impeller and spin it fast. Pumps come in all shapes, sizes and speeds. The speed is what’s really important. It’s measured in Horsepower and it ranges from ¾ horsepower to 3 horsepower, on average.

Smaller pools don’t require as much horsepower as a larger pool. So, the bigger the pool, the bigger the pump and motor.

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The Filter

Once the pump has sucked the water in, it immediately pushes out into your filter. You filter cleans out the water of fine debris and then it moves back into your swimming pool. There are three types of filters to clean your swimming pool: sand If you click this link and make a purchase, we earn a commission at no additional cost to you. , a D.E. (diatomaceous earth) If you click this link and make a purchase, we earn a commission at no additional cost to you. , and cartridge If you click this link and make a purchase, we earn a commission at no additional cost to you. . They all filter out tiny particles from your pool water.

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Extra Equipment

What we just talked about are the main ingredients to a functioning swimming pool, but you can always add more the party.

A Heater

I think this goes without saying, but yes, a heater heats up your pool water. It’s a nice feature to have on your swimming pool and you can get it on both above ground and inground pools. There are a few types of pool heaters including natural gas If you click this link and make a purchase, we earn a commission at no additional cost to you. , propane If you click this link and make a purchase, we earn a commission at no additional cost to you. , electric If you click this link and make a purchase, we earn a commission at no additional cost to you. and solar If you click this link and make a purchase, we earn a commission at no additional cost to you. . Although, it’s not a necessary piece of equipment when it comes to circulation and cleaning your pool, it’s just awful nice to have.

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A Chemical Feeder

This handy little piece of equipment makes adding pool sanitizer easy If you click this link and make a purchase, we earn a commission at no additional cost to you. . Just fill it full of the correct sanitizer (i.e. chlorine, bromine or a mineral cartridge) and let ‘er rip.

This is the last piece of equipment in your filtration line. The order of equipment is as follows:

You don’t want to add the chemical feeder before a heater because the water coming out of the feeder has got a bunch of chemicals in it and will take a toll of the inside of a heater over time.

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In Conclusion

This is the basic anatomy of a swimming pool. Everything we talked about should give you a general idea on how a pool operates. To sum it up, the water in your pool is sucked into the filter by the pump from the skimmers. The water then runs through your filter (sand, D.E. or cartridge) and is pushed back into your swimming pool via the return jets.

Hopefully, this very basic understanding should lay the ground work for proper pool care so that you and your family and friends can enjoy a crystal clear and clean pool all season long.

My 3 Cs of pool care include: cleaning, circulation and chemicals. I suggest you read these posts to understand how to keep your pool clean and healthy all season long:

Happy Swimming!

Matt Giovanisci, the founder of Swim University®, started in the pool and spa industry at age 13 and moved to bigger companies along the way, helping thousands of pool and hot tub owners every year. He wanted to share his knowledge and unique teaching style on a larger scale, so he launched Swim University® in 2007. Since then, he's worked to make pool and hot tub care easy for over 10 million homeowners. And each year, he continues to help more people with water chemistry, cleaning, and troubleshooting.

Frustrated by adding chemicals and trying to keep your pool clear all the time?

We cut out all the confusion of pool maintenance in this easy-to-read illustrated ebook and video course. It'll help you save $100 right away on pool care!

Click here to learn more
The Pool Care Handbook

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