Sand Filter Care and Maintenance

One great advantage of high-rate sand filters is easy maintenance. If backwashed regularly, modern sand filters can go many years without having to change the sand.

How Sand Filters Work - sand pool filters clean the pool water by a process called depth filtration. As the dirt penetrates the sand bed, it is trapped in the tiny spaces between the grains of sand.

Backwashing Makes the Difference - Backwashing a sand filter regularly is the key to trouble free filter performance. If the filter isn't backwashed often enough, dirt particles will build up on the surface of the sand bed. This will result in short cycles, channeling, and inefficient filtration. On the other hand, if a sand filter is backwashed too often, some of the dirt particles will pass through the sand bed and return to the pool.

How Often Does a Sand Filter Need to be Cleaned - One way to know when it is time to clean a sand filter is when the water is cloudy and/or just doesn't sparkle the way it usually does. But the best way is to document and monitor the filter's pressure gauge. If the sand filter system has both an inlet and outlet pressure gauge, the pressure differential will be low (3 - 5 psi) when the filter is clean. In most high-rate sand filters it's time to backwash when the pressure differential reaches 16 - 20 psi. If the sand filter has only an inlet pressure gauge, the filter should be backwashed when the pressure increases by 8 - 10 psi.

What Clogs the Filter - there are many different that can affect how quickly the filter gets dirty and clogged. A sand filter on a newly plastered pool can become clogged quickly with the plaster dust resulting from the new plaster pool start-up procedures. Also, dirt, leaves, other debris, algae, and heavy bather load can accelerate the shortening of filter cycles.

How to Backwash the Sand Filter - Backwashing a sand filter is simply reversing the flow of the pool water back through the filter in the opposite direction and sending the outlet water to waste. The procedure is simple. Turn off the pump. Move the filter valve to the backwash. Restart the pump. The typical sand pool filter system will need to be backwashed for two to three minutes. (consult the manufacturer service manual for specific backwashing procedures). After backwashing, turn the pump off and set the valve to the Rinse setting. Turn the pool pump back on for 30 - 60 seconds in order to make sure all the dirty water from the backwash cycle is sent to waste and not returned to the pool. Stop the pump one last time and set the filter valve to the Filter setting. Start the pump and the job is complete.

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