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The Filtration of Your Pool by Crystal Enterprises Ltd


Your pool filter has been designed as a highly efficient dirt collector; it is essential that you remove the dirt that accumulates. On Above Ground Pools that are equipped with Sand Filtration a process known as “Backwashing” is used to clean the Filter. Backwashing involves reversing the flow of water through the filter sand for several minutes. This process removes dirt trapped in the filter sand, the dirty water is pumped to waste.

It is not possible to clean Cartridge Filters by backwashing. Cartridge Filters need to be physically removed before they can be cleaned. (refer to your pool installation/operation manual)

How long should I operate my Circulation System for?

Different pool manufacturers specify different run times for filter systems. The general consensus from pool professionals is that to ensure high water quality you should run your pool filter system for at least 8 hours a day. You should increase this during peak summer months to at least 12 hours per day. If your pool is heated you will possibly need to operate the circulation system for longer periods to allow the heater to achieve the desired pool temperature. If your pool becomes green or cloudy you will need to filter the water continually until the problem has been remedied. Shortening your filtration cycle will usually prove to be a false economy.

A key component on any swimming pool circulation system is a Time Clock. When setting your Time Clock it is worthwhile splitting the daily run time into at least two segments; e.g. If you decide to operate the circulation system for 10 hours per day you should split the 10 hours into 5 hours in the morning and 5 hours in the evening. You should avoid running the filter when the pool is being used.

As with all electrical equipment on your pool, the Timer should be linked to An Earth Leakage Circuit Protector Device. (E.L.C.P.)

Cartridge Filters

Cartridge Filters, as opposed to Sand Filters, will sometimes be supplied on Above Ground Pools. Cartridge Filters have the advantages of being smaller, and cheaper than Sand Filters. However, Cartridge Filtration is not as efficient as Sand Filtration; if your pool is fitted with a Cartridge Filter and you repeatedly experience water quality problems you should consider upgrading to a Sand Filter.

If your pool experiences clarity problems you should use a Clarifier to enhance the performance of your Pool Filter. Very small particles of dirt suspended in your pool water will be too small to be caught by your Pool Filter; this often results in cloudy pool water. Pool Water Clarifiers work by attracting the small particles of dirt suspended in your pool water. As the smaller particles are clumped together into larger particles your pool filter will be able to trap them. A multitude of Pool Water Clarifiers are available from your Pool Dealer. Choose your Pool Clarifier carefully; in general, the tablet, granular and gel type Clarifiers available from your Pool Dealer are not compatible with Cartridge type filtration. The liquid clarifiers available from your Pool Dealer are usually the most effective on pools fitted with Cartridge Filtration.

It is essential that the Cartridge Elements are kept clean at all times. They should be removed, hosed down and soaked in a solution of Cartridge Cleaner. Your local Pool Dealer will be able to supply you with a product specifically formulated for cleaning cartridges. Wear rubber gloves when handling these products, they are highly concentrated. Cartridges should be soaked in a bucket overnight and thoroughly rinsed before being reused. Don’t be tempted to use a household-cleaning product or put them in your dishwasher; this will do more harm than good. You should buy a spare Cartridge Element, this will prevent your filtration system being out of service when your original Element is being cleaned. Cartridge Elements should be replaced at the beginning of each season.


To improve the quality of your pool water, run the filtration for 24hrs per day during the busy season. The longer the filter is left running, the better the water quality. The increased cost of running your Pool Circulation Pump for 24 hours per day will be more than offset by the savings made in water treatment products.

Sand Filtration

Larger Above Ground Pools will incorporate a Sand Filter, rather than a Cartridge Filter. Sand filtration is an effective means of physically removing particles from your pool water. Your sand filter will incorporate a Multiport valve. Your Multiport valve controls the various functions of your filtration system; it is essential to understand it’s various settings. A Multiport will typically incorporate the following settings:


You should consider filter to be the normal setting for your Multiport Valve. Whilst the Multiport is set in this position, Pool Water is drawn through the pump, passed into the top of your filter and pushed through the filter media, trapping suspended matter. At the bottom of your sand filter is a set of “laterals”; these act as an underdrain system and will allow your pool water, but not the sand to return to the pool.


Sand Filters are designed to accumulate dirt. It is important that they are cleaned regularly; this process, commonly known as backwashing, should typically be carried out every two weeks. Backwashing involves reversing the flow of water through the filter for several minutes, or until the site glass shows clean water. During this process the water is automatically discharged to waste, taking the accumulated dirt with it.
Before carrying out a backwash ensure that the water level in your pool is at least 50mm above the skimmer centreline. Never allow the pool water level to drop more than half way down the skimmer during normal operation.


This setting should be used immediately after backwashing, but only for 10 – 20 seconds. Your pool water follows the same path as when on FILTER, except the water exits to waste rather than returning to your pool.


This setting should be used if your filter is temporarily out of action. Pool water will be circulated, bypassing the filter tank. RECIRCULATE is useful for retaining heated water even if your filter is not being utilised.


Takes water from your pool, bypasses the filter and runs to waste. By using this setting when vacuuming a heavily contaminated pool you will prevent your filter from becoming clogged.


Must only be used when the pump is shut off. Used to isolate the circulation system during maintenance.


The sand in your filter will lose its sharpness over a period of time and become less effective. It is a good idea to change filter sand every 3 years or so. It is essential that the replacement sand is swimming pool grade.

Over a period of time the sand in your filter may become coated with oils and other contaminants. Contaminated filter sand is an ideal environment for bacteria. To minimise filter contamination you need to clean the sand at least once per year using a proprietary cleaner. Filter Cleaners are highly concentrated; wear gloves when handling these products.

Typical Setups


This article was published on Wednesday 28 September, 2011.
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