How do I know if my sand filter needs replacing?

Do you care about your health and the proper functioning of your swimming pool? Then, you will surely know that proper maintenance and cleaning of the entire water filtration system is absolutely essential.

Many times, the sand becomes so saturated with organic debris, skin, hair, and grease that it is no longer able to filter enough water to keep it transparent. To properly maintain the pool filtration system, it is important to periodically change the sand in the filter.

How do I know if my sand filter needs replacing?
How do I know if my sand filter needs replacing?

Of course, nothing is impossible. With this small handbook, we will guide you step by step in all the fundamental phases on how to change filter sand in a pool filter, without becoming mad and without wasting precious time.

When do you have to change the filter sand?

It is usually advisable to renew the filter sand every 3 or 4 years. Meanwhile, in the case you use chemical treatments with copper sulfate (multi-action tablets), it would be advisable to do it every 2 years.

In any case, the first thing you should do is make sure of the model and the specifications of your filter to see how much sand you need to replace.

For example, if your pool is 48m3, we assume that the filter should be around 14m3/h. The models of these capacities work with loads of 100 to 150kg of sand.

Sand Loads of the Filter

Here is an example of sand loads depending on the capacity of the filter. However, it is convenient to verify what load your particular filter model needs. You can check the instruction manual or by contacting the manufacturer of your filter directly.

  • For filter of 4m3/h – Sand load: 25 kg
  • In the filter of 5m3/h – Sand load: 40 kg
  • The filter of 7.5m3/h – Sand load: 70 kg
  • For filter of 9.5m3/h – Sand load: 100 kg
  • Filter of 11,5m3/h – Sand load: 150 kg

Note, these figures vary depending on the model and manufacturer of each filter.

Once you’re clear on this, let’s return to the work that now concerns us:

Method 1

Ingredients you will need for the task

  1. Vacuum cleaner
  2. Resistant and insulating adhesive tape
  3. Screwdriver (manual or electric as you prefer)
  4. Sand for the filter (remember, the quantity depends on the type of filter).

Step 1: Turn off the pool filter and allow the water to drain

First and foremost, if you do not want to be badly electrocuted and if you do not want to burn your pump, you must first switch off both the pump and the filter. After this, check that the timer is set to OFF and disconnect the power supply. Now, you have the go-ahead to remove the drain plug from the bottom of the tank and let all the water flow out. Meanwhile, it will take a little bit. So, arm yourself with patience and maybe some snack or newspaper.

Step 2: Remove the selector valve

Once you finish draining all the water at Point 1 – it’s time to remove all the pipes connected to the selector valve. If the valve is strongly sealed to the PVC pipe, it will be necessary to cut that pipe and install a suitable pipe union. This is a small sacrifice now to be able to change the sand more easily the next day. After the brief sad moment, equip yourself with screwdrivers. Next, remove and disconnect the clamp or collar that binds the valve to the tank. Once done, pull the selector valve to remove it.

Step 3: Cover the hydrant

Inside the tank, you will see the pipe goes down in the middle of a lot of dirty and dated sand. Before proceeding further, we advise you to cover the upper part of the hydrant with the insulating adhesive tape to prevent – during the removal and addition process – the sand from ending up in it.

Step 4: Remove the sand

Next, transform yourself into the perfect housewife and take out the vacuum cleaner: remove all the sand. If some bad soul had before then stolen your vacuum cleaner, dig it by hand and you’ll see that biceps.

Step 5: Rinse the tank and the side tubes

By now, you will clearly see that the arms of the side tubes come out of the main hydrant. Run to get a garden pump and rinse the sand from the remaining filter. And while you’re at it, take the opportunity to check that the tubes are well, or that they are not damaged or cracked. However, In the unfortunate event that they are, you will need to replace them immediately before adding the new sand. Otherwise, you will find it in the pool water.

When you’ve emptied the filter, the lower part is the more delicate one: be careful not to twist or bend the arms that form the star too hard because they break up easily. Meanwhile, if your cheap filters eventually break, then you have to replace them. However, in the more expensive ones, it is possible to repair the arms.

Step 6: Fill the tank halfway with water

Put the drain plug on the tank back in its place and then fill it with half water. Why? Because by doing so, the falling of the new sand that you will subsequently pour, will be muffled and will not impact heavily on the pipes risking to break them.

Step 7: Add the new sand

Unless you are Hercules in person, we advise you to put one bag of new sand on the tank at a time because they are very heavy. Cut it only once you are well positioned and let the sand flow slowly into your filter. Unfortunately, it may be necessary to repeat the operation depending on the size of your tank. Do not rush to finish the job and make sure the hose is always covered. Otherwise, you will find yourself sweeping the sand from everywhere.

Step 8: Fill all the water tank

By now, you should be almost there. Now that all the new sand is in the filter, you can add the rest of the water to fill it. However, be sure to firmly reposition the selector valve, collar, and tubes.

Remember that the technical data sheet of the filter specifies the amount of sand that goes into it. In any case, put enough to cover the inlet tube. In this way, an expansion chamber for the sand will be left.

Step 9: Backwash and rinse the filter

Set the selector valve to the Backwash item and then turn on the filter and the pump. Make yourself comfortable for 2/3 minutes. Leave it to rinse thoroughly. This is for the impurities accumulated inside the tank to flow out. Once this is done, turn off the pump. Then, set the selector valve to Rinse. After that, turn it back on, making sure to rinse the filter for a couple of minutes.

Remember, the law in many countries establishes that the wastewater of the swimming pool – containing chemical products – must decant at least 24/48 hours in a watertight Imhoff cockpit before you can use them for irrigation.

Step 10: Reset the sand filter

Congratulations, you have just changed the sand of the pool filter. Enjoy the moment and turn off the pump to set the valve to the Filter indication and reactivate the pump.

Meanwhile, while checking everything, check the pressure gauge for safety. Remember that the value of normal pressure in the filter is between 0.5 and 1.5 Bar (or between 0 and 4 PSI in American measurements). If you notice any “buzz” on the rise, you will have to wash the filter again.

Method 2

The task of replacing the filter sand is not entirely simple. However, it can be more or less complicated depending on the specific model of your filter. Are you are still not clear with the explanation in the first method? Go through the next one below and if you are still not clear, we recommend you contact a professional.

However, if you decide to still do it yourself, the procedure to follow would be as follows:

Step 1

The logic behind never changing the filter sand is that the dirty sand filters are better than the brand new one. The downside is that after a certain time, the sand will no longer be able to filter the water well enough. From the manufacturer’s point of view, they usually recommend that you change the sand in the filter every 3-4 years. This will maximize the effectiveness of the filter. Again, it will help you keep the water clean and transparent.

Step 2

Removing the sand with a vacuum cleaner will be much easier than emptying the sand by hand or with a small shovel. The sand in an old filter could be full of bacteria. Therefore, minimizing direct contact with the sand would be better.

Step 3

After removing the old sand, you will need to add water to the tank before adding new filter sand. In essence, this water will help absorb any shocks from the sand that would fall on the side assembly. Meanwhile, many professional installers skip this step. However, this is not recommended if it is the first time that you are changing the filter sand.

Step 4

The type of sand you will add to the filter will be silica sand which they produce specifically for the filters. This sand has a diameter between 40 and 50 mm and is available in most pool accessory stores. Do not replace it with other types of sand, or you will almost certainly have problems with the filter and potentially you could even damage the pool.

Step 5

The amount of sand you will add to the filter will depend on the size of the filter you have. Therefore, you need to make sure you find accurate information on how much sand you use in your filter. Filling the filter beyond due or insufficient will cause, at a minimum, its incorrect operation. In the worst case, the filter will be damaged. The range of filter sand sizes typically ranges from 45 or 70 to 270 kg or more for larger pools.

Step 6

Make sure you don’t let sand in the opening, which will be wide open. It is difficult to keep the sand in the filter without holding it in the container. So, you may have to seal the opening of the container to prevent the upturned sand from returning back to the pool through the nozzle lines. It is also very important that the container is directly on the center of the filter since, once the sand has begun to fill the filter, you will no longer be able to adjust the position of the container. However, if you do not hit the filter, you will no longer be able to recover the valve head on the filter and you will have to start all over again.

Step 7

Once filled, you can replace the filter head making sure to tighten it securely. For this reason, a capable hand would be useful, since if you tighten the filter head too much you could break the body of the filter and you will need to replace the entire tank – something you would definitely like to avoid.

Step 8

Once they are together again, the first thing you should do is give the filter a thorough wash. Firstly, you should start this operation by filling the pool beyond the usual and then backwashing for about 3-5 minutes, followed by a 60-second rinse cycle, before setting the filtering.


It is normal for sand to go back into the pool or through the drain line when you change the filter sand. This is because part of the sand you received will be smaller than #20 and this smaller sand will eventually go away from the filter. However, the long initial backwash, which you do when you change the sand, will help minimize this phenomenon.

The video tutorial should further assist you in this task:

Do you have any questions? Feel free to use the comment section. Don’t forget to like and share this article.

Read more:

How to change sand in your pool filter

Ideal salt level for pool

Green pool water after rain