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Operating Your Sand Filter

Operating Your Sand Filter

The oldest and most popular method of filtration is sand. 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 serve to separate particles, allowing filtration to take place. Sand filters are the least expensive of the three types of filters but only filters particles down to 20 to 40 microns in size. Operating your sand filter would require some knowledge but still one of the easiest ways to keep your pool clean.

Here are a few tips to remember before you get started Operating Your Sand Filter:

  1. Always shut filter off before moving valve handle. (Valve handle will be seriously damaged if you do not.)
  2. Always backwash the filter immediately after adding new sand to the filter.

Operating your sand filter

Starting the Filter System

Before plugging in filter, turn valve handle (located on top of filter) to the backwash setting. Water will begin to flow out of the backwash port plug in filter briefly until water begins to run clear. (if you need to send backwash water a longer distance, backwash hoses are available in 25, 50, 100 & 200ft lengths). Unplug filter, turn valve handle to filter position and plug in filter. You are now filtering your pool water.

Pressure reading on pressure gauge, will be between 6-12 psi. This initial pressure will be your normal operating pressure. When water return flow becomes weak or there is a surge in the pressure gauge reading it is time to backwash.

What is Backwashing?

Backwashing completely clears filter of all dirt & debris by reversing the flow of water through the filter. To backwash, simply unplug filter and move valve handle to the backwash position. Then plug in filter and let water run until clear. When water runs clear unplug filter, move valve handle back to the filter setting, and you are ready to filter again.

How long should filter run each day?

Most Sand Filters turn over approximately 2400 gallons per hour. It is recommended that you turn over the water in your pool at least twice a day (refer to chart at bottom of page for your pools capacity). Run filter more in hot weather or with heavy bather load. As a general rule of thumb, turn your sand filter on 1 hour per 10° F of weather.

Pool Capacity Cheatsheet

Capacity (Gal.)
Capacity (Gal.)
10 Round2,0008x12 Oval3,000
12 Round3,0008x14 Oval3,000
15 Round5,0008x19 Oval3,500
18 Round7,50010x15 Oval3,500
21 Round10,00010x16 Oval3,500
24 Round14,00010x21 Oval5,000
27 Round18,00012x18 Oval5,000
30 Round21,00012x24 Oval7,500
33 Round28,00014x20 Oval7,500
14x25 Oval10,000
15x24 Oval10,000
15x30 Oval12,000
16x26 Oval12,000
16x32 Oval13,500
18x33 Oval16,000
18x40 Oval18,000
Please note: Pool calculations below have been rounded off to be used as a quick guide for easy pool maintenance. For exact calculations please use our pool volume calculator.
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Tom Gallo

Pool Specialist at The Pool Factory
Tom has many years of experience in the pool industry and his knowledge and expertise are a wonderful resource for customers of The Pool Factory. Tom works with prospective customers interested in above ground/semi in-ground pools. Tom orchestrates all aspects of above ground pool sales and scheduling of delivery and will work with customers afterwards in the care and maintenance of their pool.

Have a question or comment?

  • comment avatar Julianne Bowers May 4, 2013

    We just bought a house with a sand filter pool, and are turning it on for the first time. When it is on “filter” setting, water is coming out of the blue hose that I assume is the backwash. Does that mean the filter is broken?

    • comment avatar The Pool Factory Staff May 22, 2013

      The backwash valve may need replacement or most likely the filter hoses were hooked up incorrectly.

  • comment avatar Samuel May 31, 2014

    The pressure gauge on my Hayward sand filter fills water as I use my filter, what can be the cause?

  • comment avatar Susan June 24, 2014

    My pool has been cloudy since installing a sand filter. I followed instructions and have new sand. What do I need to do?

    • comment avatar Tom Gallo June 25, 2014

      This is a common problem when installing new sand but not completely cleaning the sand before use. New filter sand has a lot of fine sediment that can cause cloudy water. If the sediment has settled on the bottom of the pool we would recommend vacuuming on the waste setting to remove it from the pool.

      If you can’t see the bottom of the pool because of the cloudy water we would recommend the following:

      1. Balance the PH and the Alkaline levels.
      2. Raise the chlorine level to 5ppm.
      3. Run the filter continuously for at least 72 hours or until the pool clears.

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