Sand is the oldest and most popular method of filtration. Sand filters share two things in common:

When in the filtration mode, water always flows from top to bottom
They all have some sort of lateral or underdrain with slots to hold back sand while allowing clean, filtered water to pass through.
High-rate sand filters use a special filter sand, normally .45 to .55 mm (also known as pool grade #20 silica sand), because it has sharp edges that separate particles, allowing filtration to take place. They operate on the basis of "depth" filtration where dirt is driven through the sand bed and trapped in the spaces between the sand particles. Initially, a clean sand bed removes larger particles, and then, as the bed starts to load up with debris, the filter removes finer particles. The sand can be cleaned by backwashing which involves reversing water flow through the filter to the "waste" line. Sand Filters trap debris as small as 20 to 40 microns.

Superior filtration from the inside out.
The Pro Series filter features an integral top diffuser that evenly distributes unfiltered water over the sand media bed in a cascading, umbrella-like pattern. This allows the greatest filtration possible from every square inch of sand. Then the self-cleaning underdrain assembly, with its 360° slotted laterals, provides a fast, balanced flow of clear water back to the pool while allowing for more thorough backwashing. Best of all, the Pro's full-flow technology reduces your energy costs because the filter operates for shorter periods.
Seven-position valve puts you in control.
The patented, multiport control valve developed by Hayward was designed with seven pool filter positions. An easy-to-use lever-action handle lets you quickly dial any function.

Long-lasting convenience.
You can easily access the Pro Series filter assembly for simple servicing via the unique folding ball joint in the laterals. A corrosion-proof housing protects the filter from severe weather for years to come.

Pro Series Specifications
Filter type: High-rate sand: No. 1/2 silican sand (.45 mm - .55 mm)
Filter tank: Molded polymeric
Underdrain: 360° self-cleaning slotted laterals, precision installed in ball-joint assembly
Control valve: Four or seven-position, top-mount Vari-Flo™ valve with level-action handle
Valve fastening: Flange clamp design
Pump and motor: PowerFlo Matrix Series Pump - 115 volts
Mounting base: Injection-molded ABS

** REQUIRES 150 LBS OF SAND OR 75 LBS OF ZEOLITE (SOLD SEPARATELY) **