The best type of filter depends on the usage of the pool as well as the preferences of the pool owner/operator and the local city codes. The chart below will help you to determine the best filter for your situation.
|Filter Media||Sand||Diatomaceous Earth||Paper Filters|
|Cleaning Method||Internal Backwash||Internal Backwash||Disassemble and Clean with Hose|
|Backwash Line Required||Yes||Yes||No|
|Frequency Of Cleaning||Every Week||Every 4-8 Weeks||Varies Widely, depending on unit|
|Recommended Application||Home Pools
NOT for Apt. Pools
NOT for Apt. Pools
|Water Clarifier Needed?||Sometimes||Never||Sometimes|
|How Often Media Replaced?||6 years (home use)
3 years (apt. use)
|Each Backwash||2-4 years|
|Cost to Replace Filter Media||$50 - $100 for sand (excludes labor)||$2.00 - $4.00 for DE
$200 - $300 for a new set of grids (excludes labor)
|Varies, but can be VERY expensive|
|Annual Maintenance||None Required||DE Filter Clean $75.00||Cartridge Cleaning periodically.|
|Positive Points||Easy to backwash
Filter Media (cheap0
|Best filtration||Simple to maintain
Easy to repair
"Wastes" water in weekly backwash
|Backwash a bit complicated Repairs not cheap.
Not allowed in every municipality
|Cartridges can be a bit costly, check cost before buying filter.
Filter cleaning not as easy as others
The choice of filter for a home pool is largely up to the consumer. Any type of filter will work, but sand filters will not filter as finely and this can create water clarity problems from time to time.
DE and Cartridge filters should NOT be used on semi-public pools (apartments, condos, hotels, etc). The manufacturers may try to sell them for this application, but they are not the best choice. The problem is that with their finer rate of filtration, they fill up with dirt very quickly and become clogged and ineffective. I have seen a lot of DE and Cartridge filters that have been pulled off of semi-public pools after only a few months or years.. In these cases, the owner had to foot the bill to have a new sand filter installed. In some cases, where it is not possible to install a backwash line for the pool, a Cartridge filter may need to be installed, but it should be done with the expectation of higher maintenance labor and parts costs.
Once you have chosen the right type of filter for your pool, it is important to get it sized properly. It must be sized to match the pump which in turn must match the circulation needs of the pool. If the filter is undersized, it will fill up quickly and also can be damaged by the force of the pump. If the filter is undersized, it may not backwash well.
|Recommended flow rates for different sizes of SAND FILTERS|
|Tank Diameter||19 "||21 "||24 "||30 "||36 "|
|Surface Area||1.8 Sq. ft.||2.3 Sq. ft.||3.1 Sq. ft.||4.9 Sq. ft.||6.9 Sq. ft.|
|Max Flow Rate||40 GPM||50 GPM||60 GPM||100 GPM||140 GPM|
|Recommended flow rates for different sizes of D.E FILTERS|
|Surface Area||24 Sq. ft.||36 Sq. ft.||48 Sq. ft.||60 Sq. ft.||72 Sq. ft.|
|Max Flow Rate||48 GPM||72 GPM||96 GPM||120 GPM||144 GPM|
|Best Flow Rate||36 GPM||54 GPM||72 GPM||90 GPM||108 GPM|
|Recommended flow rates for different sizes of CARTRIDGE FILTERS|
|Surface Area||100 Sq. ft.||200 Sq. ft.||300 Sq. ft.||400 Sq. ft.||500 Sq. ft.|
|Max Flow Rate||38 GPM||75 GPM||112 GPM||150 GPM||150 GPM|
|Best Flow Rate||30 GPM||50 GPM||75 GPM||100 GPM||125 GPM|
Note that these recommendations are only approximations based on typical conditions.
On-site analysis must be done to insure that the filter matches up properly with the pump and the pool. For instance, if the plumbing runs on the equipment are particularly long, then the resistance to flow in the piping will be greater and intake lines may need to be larger than specified in this chart.
Note also that this may differ from the recommendations listed by the manufacturer.
The literature may indicate that it is OK to match up a 2.5 or 3.0 hp pump to a 60 square foot DE filter, but we never recommend it because we have seen plenty of DE filter grids blown out by these larger sized pumps. It is always better to oversize the filter. With an oversized filter, the water flows through the filter media at a slower velocity and that results in finer filtration and longer filter cycles.
Some builders will install a 3.0 hp filter pump on a pool/spa combination in order to give maximum water flow through the spa jets.
This is nice except for the fact that the pump is so powerful that it has the potential to damage the grids in the filter. The better way is to install a smaller filtration pump for the pool and then run a separate booster pump. This keeps you from having to run a large 3.0 hp pump every day on the normal filter cycles.