Pool sand filters are the most reliable, low maintenance, environmentally friendly and efficient pool water filter on the market.

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!

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.

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

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.

This image shows a gunky, worn out #20 silica medium inside pool sand filter.