Pool filters: sand, cartridge, and more

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Preguntas frecuentes sobre Pool filters

How do you choose the right pool filters based on the water volume?

Choosing pool filters requires calculating the required flow rate by dividing the total water volume in cubic meters by 4 hours. For example, a 40 m³ pool requires a system capable of filtering at least 10 m³/h to complete the recommended daily circulation in 2026.

Consider these technical criteria before deciding what to buy:

For pools up to 20 m³: a Ø300 mm tank with an integrated compact pump.
For pools from 20 to 45 m³: a filtration unit with a diameter of Ø400 mm or Ø450 mm.
For pools over 50 m³: Ø500 mm or Ø600 mm laminated filters with a side-mounted selector valve.

An undersized filter will clog within a few days and increase the pressure inside the pressure gauge.

I have a 15,000-liter above-ground pool with a small pump. What complete system should I install?

For a 15,000-liter above-ground pool, a compact 4 m³/h monobloc unit mounted on a single base is a good choice. This configuration addresses the lack of power in basic cartridge pumps and purifies the entire volume in less than four hours of continuous operation.

A proven option for this volume is the Star 300 sand filter with pump, which includes standardized connections, a durable tank, and a motor assembly sized to prevent excess pressure. It is ready to use straight away and works with both silica sand and granular glass, without requiring additional plumbing adapters on the outlet.

What is the difference between a top-mounted TOP selector valve and a side-mounted valve?

The main technical difference lies in the location of the hydraulic connections and ease of access for internal maintenance. The top-mounted valve screws directly onto the top opening of the tank, reducing the horizontal space occupied in the equipment shed.

In contrast, the side-mounted selector valve is installed on the side of the tank using two separate ports. This side-mounted design lets you open the top of the filter tank to inspect the filter bed or replace the sand without having to remove the suction and return pipes.

The pressure gauge on my pool filter rises after two days of use. Why does this happen, and how do I fix it?

A rise in pressure on the pressure gauge indicates that the filter media is clogged with trapped dirt or that the pump is delivering excessive flow. When the needle rises 0.3 or 0.5 bar above the normal operating range compared with the initial clean pressure, immediate backwashing is required.

To safely resolve this issue, follow these technical steps:

Turn off the pump before moving the selector lever to the wash position.
Backwash for 2 or 3 minutes until the clean water appears in the transparent voyant.
Select the rinse position for 30 seconds to settle the sand.
Stop the system and return the lever to the filtration position before restarting the circuit.

Remember, never move the handle while the motor is running, to protect the internal gasket.

How often should the filter media in pool filters be replaced?

Silica sand in pool filters should be replaced every 3 or 4 seasons of intensive use. Continuous water friction wears down the sharp edges of the quartz grains, reducing their mechanical filtration capacity and encouraging the formation of preferential channels that return dirt to the pool.

If you use activated filter glass, replacement intervals increase to 8–10 years thanks to its lower bacterial adhesion and unchanging structure. To upgrade an existing installation, you can connect the Starpool Ø400 mm sand pool filter without pump, with selector valve to your current suction system without changing the pipe diameter.

The handle on my Hayward filter has broken, and it's leaking water through the drain. Do I need to replace the whole tank or just the valve?

You don't need to replace the tank if the filter body remains structurally watertight. Constant water loss into the drain line is usually caused by deterioration of the star gasket or the selector valve's internal cam due to normal wear or rough operation while the motor is running.

To fix this fault, simply install an original replacement part such as the 6-way 1½" valve (SP0710X62E), which is fully compatible with standard filters with 1.5-inch threaded connections. This direct replacement fully restores the seal across all six operating positions without requiring you to replace the sand.

What problems can result from installing a pump that is too powerful for the filter diameter?

Installing a pump with a flow rate higher than the tank can handle causes a hydraulic phenomenon known as internal turbulence or forced fluidization. When the flow exceeds the recommended filtration rate (generally 50 m³/h per m² of filter surface), water passes through the sand bed at high speed without depositing tiny particles.

This sizing error causes serious operational problems:

Water returns to the pool jets with constant turbidity and fine dirt particles in suspension.
The lower laterals are subjected to excessive mechanical stress, which can break their plastic slots.
Sand is expelled into the pool because it is not retained at the bottom of the tank.

Always maintain the manufacturer-recommended ratio between the motor power and the filter's flow rate in liters per hour.