Pool equipment explained

Nothing else works if the pump does not. Chemicals only reach the water that passes them, and the filter only catches what is pushed through it.

It is also the biggest running cost of owning a pool, usually ahead of chemicals. Pumps sold in Australia have had to carry an energy rating label since 1 October 2022, so anything older than that was never held to an efficiency standard.

We have put the numbers in their own page: what a pool pump costs to run.

Sand filters are the traditional option. Water is pushed through a bed of sand, and you backwash to clean it. Commonly quoted filtration is around the 20 to 40 micron range, and the sand itself is usually replaced every few years.

Cartridge filters use a pleated element instead. They filter finer — often quoted around 10 to 20 microns — and they do not backwash at all, which matters in a city with water restrictions. You take the element out and hose it. The element is a consumable and needs replacing every year or few.

Glass media is sand's replacement. Recycled glass in a normal sand filter, filtering finer than sand and usually lasting considerably longer before it needs changing.

The water-use difference is worth knowing. A sand backwash is commonly quoted around 300 litres, and glass media lighter and quicker to clear. Hosing a cartridge uses hose water rather than pool water, which is the same argument from a different direction.

Pool lights are the one piece of gear where the upgrade is uncomplicated: LED uses a fraction of the power of the old halogen units and lasts far longer.

The thing owners get caught by is the replacement, not the globe. On many older pools the light cannot be changed without lowering the water, and on some it is sealed in a way that means replacing the whole fitting.

So if a light has failed and the pool is due to be serviced anyway, it is worth having both looked at in one visit rather than two.

Solar is panels on the roof with pool water pumped through them. Cheapest to run by a long way, because the heat is free; the trade-off is that it only works when the sun does, so it extends your season rather than guaranteeing a temperature.

A heat pump moves heat out of the air into the water rather than generating it. It works in cooler weather and costs far less to run than gas, but it heats slowly and needs to be left on.

Gas heats fastest and costs the most to run, by a wide margin. It earns its place where you want a pool hot on demand rather than warm all season.

Suppliers publish yearly running-cost comparisons with solar cheapest, heat pumps in the middle and gas several times higher. Treat any specific figure as a sales estimate until it is worked out on your pool, your climate and your tariff — the gap between the three is real, but the numbers are not.

A cover is the least glamorous item here and probably the best value.

It cuts evaporation, which is water you are paying for and, in a heated pool, heat you are paying for. Research cited by the US National Renewable Energy Laboratory puts the reduction in water loss at roughly 30 to 50 per cent.

Suppliers commonly claim large reductions in heating costs too. Those numbers vary a lot, but the direction is not controversial: an uncovered heated pool loses most of its heat off the surface overnight.

It also keeps leaf litter out, which on a shaded block means less chlorine consumed and fewer stains — the problem behind a lot of what we see round the Upper North Shore.

Pump seals go, and you see a drip underneath before it fails properly. Bearings go noisy well before they seize.

Salt cells wear out on runtime rather than age. They stop producing gradually, so the first symptom is usually chlorine that will not hold rather than an error light.

Filters rarely fail outright. They just quietly stop filtering as media ages or an element collapses, and the water goes dull.

Almost all of it announces itself. Most of the emergency calls we get are things that had been making a noise or leaving a puddle for a month. If something has changed, it is worth having it looked at before it picks its own moment.