Swimming pool water filter systems are three basic types: sand filter, cartridge filter and diatomaceous earth filter.

1. How the contaminants come into the pool water.
Why Use the Filter
Swimming pool filter system is used to removes
• Dust
• Dirt
• Debris
• and other particulates from the water.
The contaminant come into the pool water through the –
• Environment
• Chemicals
• Or carried by the swimmers
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2. Types of Swimming pool water filter
Pool water filters are basically three types:
• Sand filter
• Cartridge filter
• and diatomaceous earth filter.
Source: http://hardsoftwater.com/swimming-pool-filter-system/

3. Pool Sand Filter
Pros
• Cheaper and easy to maintenance
• Sand last 5-7 years
Cons
• Less energy efficient
• Needed frequent backwashing about every week.
Source: http://hardsoftwater.com/swimming-pool-filter-system/

4. Pool Cartridge Filter
Pros
• No backwash
• Requires less water to clean
• Environmentally friendly
• Filter runs at lower speeds
• Larger surface area
• Traps tiny particles as small as 5-10 microns
• Cartridges are available and reasonable price
Cons
• More maintenance cost than sand filters
• Cartridges need to be clean once or twice per year
and replaced after about every three years.
Source: http://hardsoftwater.com/swimming-pool-filter-system/

5. Diatomaceous Earth Filter
Pros
• Most efficient
• Traps the smallest particles
• Provide the cleanest water
Cons
• Expensive and higher maintenance costs.
• Not the environmental friendly
• The D.E. powder is carcinogenic
Source: http://hardsoftwater.com/swimming-pool-filter-system/

6. Conclusion:
You can choose best filter for your pool by considering:-
• Pool size
• Energy efficient
• Cost effective system
Source: http://hardsoftwater.com/swimming-pool-filter-system/