Pool Sand Filter Guide

for sparkling clean pool water

What are pool sand filters? They are the most reliable, low maintenance, environmentally friendly and  efficient pool water filter on the market. Read more >  

Slow sand filtration has been around for hundreds of years and proven to be a reliable method to purify water with no chemicals.

Pool sand filters operate in a similar way by using natural sand as a filtering agent to trap debris and tiny particulates. Since sand filters don’t require paper or fibre filter components that need regular replacement, they can go on for ages with minimal maintenance.

However, sand filters do not sanitise pool water. That job is for your pool chemicals. But a sand filter plays a big role in keeping your pool water crystal clear!

How do pool sand filters work? 

Sand filters capture a range of debris and particulates. This occurs when pool water is circulated via pump through a multiport valve into the sand filter canister. From there it is sprayed or diffused over the sand inside the filter. The pool water then flows through the sand filter medium to the bottom of the canister and is expelled back into your pool via a return outlet.

All sand pumps come equipped with an internal pressure gauge. When this pressure gauge indicates a 10 kPa increase from normal operating pressure (50-75kPa), you will need to clean out the dirt and debris caught in the filter. This is achieved by a process called backwashing which is a simple semi-automated procedure that takes about 10 minutes. You should backwash your sand filter every fortnight right after vacuuming your pool. If your pool gets contaminated by leaf debris regularly, you may have to backwash more frequently unless you utilise your pool cover. Dispose waste water into your storm drain.

How to maintain & backwash a pool sand filter 

A typical pool sand filter has 6 settings including filter, backwash, rinse, circulate, closed, and waste. Once you are familiar with these control settings, and how to switch and lock them in, you can backwash your sand filter by following these steps:


  1. Switch off your pool pump
  2. Set and lock in filter multiport valve handle to “Backwash”
  3. Switch on pool pump and allow backwash for a few minutes or until the water visible through the sight glass runs clear
  4. Switch off the pool pump
  5. Set and lock in filter multiport valve handle to “Rinse”
  6. Switch on pool pump and allow the rinse cycle runs for a minute or until the water visible through the sight glass runs clear
  7. Switch off the pool pump
  8. Set and lock in filter multiport valve handle to “Filter”
  9. Switch pump back on and you’re done

Does your pool filter sand need changing? 

A typical pool sand filter holds 100 kg or more of #20 silica sand with grains that fall within the 45 to 55 millimetre range.

Replacement sand is relatively cheap and can last up to 7 years before replacing, but 3-5 years is the norm. That’s because when #20 silica sand becomes smooth & rounded through weathering, its filtration efficiency is greatly reduced (see next image).


Image: Gunky, worn out #20 silica medium inside pool sand filter.

Atlantis Pool Shop Feature Product

Evoclear S Series Media Filter

The Evoclear S Series Media Filter features the latest fibreglass technology utilising multiple layers of continuous stranded fibreglass filaments. This premium sand filter has an efficient internal hydraulic design for better pool efficiency and significant savings in your energy & water costs.

    • Suits Variable Speed Pumps.
    • Up to 30% water savings.
    • Hydraulically Balanced Flow.
    • Durable and long life.
    • Filter vessel made with the latest fibreglass winding technology
    • High quality commercial design and construction.
    • 350kPa pressure rating.
    • Fish tail laterals for hydraulically balanced flow distribution, optimal filtration and backwashing efficiency.
    • Suitable for low-powered and energy efficient variable speed pumps.
    • Filter tank and multi-port valve made of durable UV and corrosion resistant materials.
    • Six position multi-port valve with ergonomic handle.
    • Multi-port valve designed for maximum performance.
    • Operating pressure of up to 400kPa (tested to 600kPa).
    • Easy to view sight glass for easier backwash inspection.
    • Oil-filled pressure gauge to accurately assess kPa levels.
    • Inflow diffuser to evenly distribute water flow over sand filter bed.
    • Suits sand, glass and other media filtration materials.

    Shop and buy the The Evoclear S Series Media Filter today


    If you’re interested in this pool filter, contact our sales team for a great deal and installation service quote on (07) 3491 9700. You can also shop online: