How does a pool sand filter work? Simple Explanation

Are you planning to build your pool this summer? If yes, then you will surely want to know more about keeping the pool clean and healthy. While building a swimming pool, you will come across the mention of filtration. Here, we are going to talk about how does a pool sand filter work?

Just like we drink clean water, the swimming pool also requires fresh water. This is made possible by the constant circulation of water through sand filters as well as by adding chemicals. Today,

Rather than being a new concept, sand filtration has been used for ages. The sand helps to encapsulate debris present inside the water and helps to keep it clear. But, you will surely need to learn a bit more when using a sand filter with your pool.

Hence, we are here to help you out with demystifying the need to install the filter to your pool. Let us learn about the magic that a sand filter does to your pool or spa water!

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What is a pool sand filter?

Setting up a swimming pool is not as easy as it may seem. Sometimes you will be perplexed to know about all the parts that make up a pool. Apart from taking a dip in the fresh water, you will also need to think about keeping the water fresh and clean.

A sand filter usually looks somewhat like an oversized oxygen cylinder. The device gets along with the circulation system and helps to rid the water of any debris. So, if someone is getting into the pool with dirty feet, this filter will help take care of it.

The sand filter gets its name from the sand present inside it. But, in certain cases, the sand is actually made up of mesh crystal silica, glass, and even zeolite. When you buy a sand filter, it will surely come with instructions to use it properly.

Apart from sand filters, the cartridge filter is also seen, but the sand filter is the easiest to maintain. It also works the best for homely pools as well as for commercial pools. As a rather inexpensive option, pool enthusiasts have been vouching for these filters.

How does a Pool Sand Filter Work?

How does a pool sand filter work?

Filtration process of a pool sand filter

Now, even though the anatomy of a pool sand filter will depend on its model, we will try to simplify it for you. As we have told earlier, in this filter, the sand or filler works as the filtration agent. In the center of this cylinder, you will find sand.

However, from the outside, you can only see the three mouths to which the pipes are attached. On one side, you will find the inlet and the outlet pipe. While on the other side there is an outlet for the wastewater, which becomes useful during backwashing.

When the filter is turned on, the pool water will enter the vessel from the top. As the water trickles down, the sharp edges of the sand catch the debris and other particles. In some models, the entry point is at the side, from which the water is then routed towards the top to begin filtration.

The filtration system only works when the water drips from top to bottom. As the water reaches the bottom of the vessel, it is trapped by the laterals or finger-like projections. These laterals have minute holes to allow only the water to get inside the pipe and back to the pool.

As time goes by, the sand gets to a cakey consistency due to the buildup of dirt and debris. This is the time to backwash the vessel to get rid of the gunk and to enhance the filtration system. After the recommended time, you will also need to change the filter media to keep it healthy.

Backwashing and Rinse

Just like the sand filter keeps your pool clean, it is your duty to keep it in good health. Backwashing is the process through which the sand is cleaned off the debris and dirt it has trapped. You will get the exact instructions along with your particular sand filter.

Generally, backwashing should take place weekly to keep the pool water as healthy as possible. When you choose to backwash, the water actually travels in a down-to-up motion. This helps in detaching the debris from the sharp corners of the sand. Due to high pressure, the water carries away the debris and eliminates it through the waste pipe.

Backwashing a sand filter is extremely easy and hassle-free. Once the backwashing is over, you will have to rinse the filter to ensure its cleanliness. It gets over within minutes, and your sand filter will be ready to work after it’s cleaned.

Changing the filtration material

Like any other filter, the pool sand filter will also need a change of the material present inside it. The good news is that it can be done after 5-7 years, depending on the frequency of pool use. And, buying a bag of filler is quite cheap, so you don’t need to worry about it.

A good thing about sand filters is that they can run for 20-25 years without much maintenance. Just make sure that you are backwashing the sand regularly to keep it fresh and clean. Also, we will recommend you use professionals to change the sand so that the laterals aren’t damaged.

After changing the sand, you will need to rinse it to give it a good start. Ensure to read all the instructions before you do anything to your pool sand filter to protect it from any damage.

If you understand above mentioned 3 steps, that’s all you need to know about how does a pool sand filter work

What can the pool sand filter remove from the water?

You must be thinking about the particles that the sand filter can remove. Well, it has a high capacity because the sharp edges of the sand can trap almost everything. So, be it a leaf or dead skin cells, the sand filter will get through everything.

However, to prolong the use of a filter, we will highly recommend removing any large debris from the pool. It is best to spend some time sifting through the water to avoid any clogging in the pipes.

What size pool sand filter should you get?

The size of the pool filter is based on the size of your pool. Sand filters work best with inground pools, but they will also work with other pools just fine.

For a pool that holds less than 20,000 gallons of water, get a pool sand filter of 24 inches. Pools having a capacity of more than 50,000 gallons will require a tank of 36 inches. If your pool falls in the in-between range of 20,000-50,000 gallons, choose a cylinder of 24-30 inches.


If it’s your first time setting up a pool, now that you know How does a pool sand filter work buying a sand filter may seem intimidating. But, we assure you that it isn’t as hard as it seems. As an easy filtration system, a salesperson will always guide you to get an appropriate model.

Make sure to take down every point about your swimming pool, like the dimensions and frequency of use. After that, you will be all set to get a brand new pool sand filter. We will also advise you to talk to a professional or a pool enthusiast before committing to a model.

Our handy-dandy little guide will surely give you an idea about this filtration system. So now, go and get yourself started on building that dream pool!

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