Work out your pool's volume in litres, then choose a pump that passes that volume through the filter about twice in 24 hours. For a 5,000 litre pool that is about 10,000 litres a day, so a 330 GPH pump (about 1,249 litres an hour) is the minimum and a 530 GPH pump gives headroom.
Pool pumps are sold in gallons per hour. Australian pools are measured in litres. That mismatch is why so many people buy the wrong size.
The conversion, and the rule
One US gallon is about 3.79 litres. So a 330 GPH pump moves roughly 1,249 litres an hour, a 530 GPH pump about 2,006, and an 800 GPH pump about 3,028.
The rule of thumb is that the whole pool volume should pass through the filter about twice in 24 hours. A 5,000 litre pool therefore needs around 10,000 litres of turnover a day. Run the pump eight hours and that is 1,250 litres an hour, so a 330 GPH pump is the bare minimum and a 530 gives useful headroom.
Rated flow is not real flow
The number on the box is measured with no resistance. Once you add a filter cartridge, hoses and a few bends, real flow is lower, and it drops further as the cartridge loads with dirt. That is the main argument for buying one size up rather than one size down.
Cartridge filters: the simplest kind to own
A cartridge filter is a pleated element in a housing. There is no backwashing and no sand to change. Rinse the cartridge with a hose weekly through the season, more often after a storm, and replace it each season. A cartridge that looks grey after rinsing is done, because the dirt is in the pleats rather than on the surface. If leaves are what is clogging it, see how to keep leaves out of a pool.
Run it during the day
Chlorine is consumed fastest in sunlight, which is exactly when the water most needs turning over and dosing. Running the pump overnight to catch off-peak power saves a little on electricity and costs more in chemicals and clarity. Split the run if you want: a few hours mid-morning and a few mid-afternoon.
Saltwater chlorinators change the running cost, not the cleaning
A chlorinator makes chlorine from salt already dissolved in the water, so you stop buying and storing liquid chlorine. The water feels softer and smells less. It does not reduce the need for a pump, a filter or a cover, and the cell itself is a consumable.
When the water goes cloudy
In order: check the cartridge is clean, check the pump is running long enough, check the chlorine level, and only then reach for a clarifier. Cloudiness in a heatwave is nearly always turnover, not chemistry.
Frequently asked questions
How many litres an hour is a 330 GPH pump?
About 1,249 litres an hour. A 530 GPH pump moves about 2,006 litres an hour and an 800 GPH pump about 3,028.
How big a pump does my pool need?
Choose a pump that passes the whole pool volume through the filter about twice in 24 hours. For a 5,000 litre pool that is about 10,000 litres a day, or 1,250 litres an hour over eight hours, so buy one size up for headroom.
When should I run the pool pump?
During the day. Chlorine is used up most quickly in sunlight, which is when the water most needs turning over. Split the run into a few hours mid-morning and a few mid-afternoon if you like.
Why is my pool water cloudy?
Check in order that the cartridge is clean, the pump is running long enough and the chlorine level is right, and only then try a clarifier. In a heatwave, cloudiness is usually turnover rather than chemistry.
What we stock
The pool pumps and filters page carries Flowclear cartridge filter pumps from 330 to 800 GPH. Pair one with a cover to cut evaporation and a cleaner or robotic vacuum to keep the floor clear. The full Bestway range, including above ground pools, is here too.
Delivered Australia-wide in 3 to 5 business days. Orders with a total value of $100 or more qualify for free shipping. 30-day returns on eligible items apply (see our return policy).