Pool filters

The most common systems are sand, cartridge, and diatomaceous earth filters, each with different filtration and maintenance characteristics.

Sand filters use granular filter media and can be cleaned by backwashing. Cartridge filters use removable filter elements that must be cleaned periodically and generally do not require backwashing. Diatomaceous earth filters use a specific filter medium and can provide very fine filtration, although they require different maintenance.

There is no universally better system: the choice depends on the pool size, flow rate, installation, desired filtration quality, and the maintenance you want to perform.

Sizing begins with determining the pool's water volume and the required filtration flow rate, but the pump, pressure losses, and the filter's own characteristics must also be considered.

The pump and filter must work properly as a unit. It is not advisable to choose a filter solely based on the pool's cubic-metre volume or install a more powerful pump without checking the flow rate supported by the filter.

Consult the manufacturer's specifications and pay particular attention to nominal flow rate, filtration speed, connections, and compatibility with the pump.

The sand filter is one of the most widely used systems due to its simple operation, ability to work with different pool sizes, and ease of maintenance.

When the filter media accumulates dirt, it can be cleaned through backwashing, avoiding the need to disassemble the filter for routine cleaning.

In addition to silica sand, certain filters may accept other filter media. Always check which materials and grain sizes the manufacturer allows before replacing the original media.

There is no fixed frequency that applies to all pools. One of the best references is to compare the pressure gauge reading with the filter's usual pressure when it is clean.

When the pressure increases above this reference value, it may indicate a buildup of dirt and the need to backwash.

Follow the pressure increase and procedure specified by your filter's manufacturer. If the valve has a rinse position or rinse function, also use it according to the instructions after backwashing.

It depends on the filter and the result you are looking for.

Silica sand is the traditional filter medium and offers a simple, economical solution. Filter glass and zeolite have different characteristics that may provide certain advantages depending on the product used.

Not all filters necessarily accept every type of filter media or use the same quantity or grain size. Before switching from sand to glass or zeolite, consult the manufacturer's specifications.

I would avoid choosing solely based on generic claims about microns, chemical savings, or years of service life.

Cloudy water does not necessarily mean that the filter is faulty. It may be caused by chemical imbalances, very fine particles, insufficient circulation, a dirty filter, deteriorated filter media, or an undersized system.

First check the water parameters and the condition of the filtration system. If the pressure gauge indicates that backwashing is required, clean the filter according to its instructions.

Certain clarifiers or flocculants may help in specific situations, but you should first check their compatibility with the type of filter and follow the dosage indicated by the manufacturer.

The filtration principle is similar, but maintenance depends on the type and size of the equipment.

Many above-ground pools use cartridge filters. In these systems, the filter element must be removed and cleaned periodically and replaced when its condition requires it.

Above-ground pools that use sand filters require maintenance similar to that of other sand systems: monitor the pressure, clean the prefilter when appropriate, and backwash when necessary.

There is no number of years that applies to all filters.

The service life of the filter medium depends on the water quality, intensity of use, maintenance performed, product characteristics, and operating conditions.

If recurring filtration problems, compaction, channeling, or other alterations to the medium occur, it is advisable to inspect it and check the manufacturer’s recommendations before replacing it.

Backwash when necessary and keep the pool water properly balanced.

Avoid overdosing chemicals or filtration aids, and use only treatments compatible with the filter medium and the equipment.

It is also advisable to periodically inspect the inside of the filter according to the manufacturer’s instructions to detect compaction, channeling, or abnormal buildup.

The selector valve directs the water flow and allows the different functions available in the system to be used.

Depending on the model, it may include positions such as filtration, backwashing, rinsing, draining, recirculation, and closed. Each one changes the water flow path to perform a specific operation.

One particularly important rule is to always turn off the pump before changing the position of the selector valve, unless the equipment’s specific instructions indicate another procedure.

During filtration, the water passes through the filter medium before returning to the pool. During backwashing, the flow is changed to clean the medium and discharge the dirt into the drain.

Rinsing is used after backwashing in systems that have this function. Recirculation, on the other hand, allows the water to return to the pool without passing through the filter medium.

Consult the valve manual because the available positions and functions may vary between models.

They use different technologies and filter media.

The sand filter stands out for its simplicity and ease of maintenance through backwashing. The diatomaceous earth filter is designed to achieve finer filtration, but it requires specific procedures and materials for operation and maintenance.

Before deciding solely based on filtration fineness, also compare the equipment cost, maintenance, availability of the filter medium, and system characteristics.

It depends on the pool and your priorities.

A sand filter can be especially practical when you want a robust system that can be cleaned by backwashing. A cartridge filter avoids this process and can reduce the amount of water used for cleaning, although it requires removing and manually cleaning the cartridges.

To decide, compare the required flow rate, available space, water consumption during maintenance, and the cost and availability of the filter elements.

In certain cases, a filter with a higher capacity can be used, but it must still be compatible with the pump and the rest of the system.

A filter should not be selected in isolation. Check the flow rate, filtration rate, operating pressure, connections, and hydraulic characteristics.

Oversizing without performing these calculations does not automatically guarantee better filtration.

If sand appears in the pool, there may be a problem with an internal filter component, the assembly, or the filter medium itself.

Common checks include the condition of the collectors or laterals, the distributor pipe, the quantity and grain size of the filter medium, and the valve assembly, depending on the filter design.

If the problem appears immediately after changing the filter sand, check especially that the grain size and quantity specified by the manufacturer were used.