Pool filtration | Filters, pumps and valves

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Preguntas frecuentes sobre Pool filtration

I have an in-ground 40-cubic-meter pool. What pool filtration equipment do I need to install?

A 40-cubic-meter installation requires a minimum nominal flow rate of 10 cubic meters per hour to recirculate the entire volume in 4 hours. This performance requires a 0.5 HP self-priming pump paired with a sand filter with an internal diameter of 500 mm.

If the filter diameter is insufficient for the pump's flow rate, water will pass through the filter bed too quickly, pushing dirt back into the pool through the return jets. You can check the technical specifications for the Starpool Ø400 mm pool sand filter without pump, with selector valve for more compact volumes of up to 30 cubic meters.

How often should pool filter media be replaced?

Silica sand with a grain size of 0.4 to 0.8 mm should be replaced every 3 or 4 years due to mechanical grain erosion. By contrast, active filter glass maintains its retention capacity for 8 to 10 years without clumping or producing bacterial biofilms.

Factors that accelerate filter media wear:

Water hardness above 300 ppm, causing the filter media to calcify.
Failure to backwash regularly, causing the filter channels to become compacted.
Continuous use of polymeric flocculants dosed directly into the skimmer.

Replacing the media in time prevents permanent increases in operating pressure and reduces the motor's energy consumption.

I've noticed that the pressure gauge rises quickly. How do I know when to backwash my filter?

Backwashing should be carried out when the pressure gauge reads 0.5 bar above the initial pressure recorded with clean filter media. This increase indicates that the buildup of particles in the silica sand bed is restricting water flow.

To restore system permeability, turn off the pump, set the selector valve handle to the backwash position for two minutes, then finish with a thirty-second rinse before returning to the usual pool filtration position. This procedure prevents thermal overload in the drive motor winding.

What pump power is suitable for a given pool filter diameter?

The relationship between motor power and filter diameter determines the water flow rate, which must never exceed 50 cubic meters per hour per square meter of filter surface area.

Recommended technical compatibility parameters:

300 to 400 mm filter: 0.25 to 0.33 HP pump for flow rates of 4 to 6 m³/h.
450 to 500 mm filter: 0.50 HP pump for flow rates of 7 to 10 m³/h.
600 mm filter: 0.75 to 1 HP pump for flow rates of 14 to 16 m³/h.

For small or above-ground pools, integrating a compact unit such as the Optima 0.25 HP Single-Phase Pump ensures a controlled filtration speed without straining the lower filter laterals.

I want to replace my entire equipment enclosure. Is it better to buy the components separately or get a preassembled kit?

A preassembled monobloc unit fully solves alignment problems between the pump and filter, saving space in underground or above-ground equipment enclosures. The shared base absorbs vibrations, and the rigid connecting pipes come factory-glued with the exact hydraulic diameter.

Choosing the Starpool Ø450 mm pool sand filter with pump and multiport valve ensures that the impeller delivers the right flow rate for the volume of sand in the filter, avoiding unnecessary pressure losses from poorly calculated suction elbows.

What are the 6 functions of a pool filter multiport valve?

The 6 positions on the multiport valve control the water flow to the filter, pool, or outdoor drain.

Filtration: runs water through the filter bed and returns it, purified, to the inlets.
Backwash: reverses the flow from bottom to top to clean out trapped dirt.
Rinse: settles the filter bed after backwashing, sending the cloudy residue directly to the drain.
Recirculate: moves water through the plumbing without passing it through the filter, to distribute chemicals evenly.
Drain: draws water from the bottom and sends it to the drain without disturbing the sand, to refresh the water or remove sludge.
Closed: stops all fluid flow so the pump prefilter can be opened.

Can I replace regular sand with ecofine glass in my filter without modifying the plumbing?

Replacing silica sand with filter glass does not require any changes to the plumbing connections or pump. The glass is poured directly into the filter tank after removing the old media and checking that the lower collector arms are intact.

The volumetric weight of glass is approximately 15% lower than that of sand, so a filter designed to hold 100 kg of silica sand will need only 85 kg of glass. Its polished surface reduces water turbidity by capturing particles as small as 5 microns and significantly lowers water consumption during subsequent washes.