Queensland had its wettest year since 2011 in 2025, with a state-wide rainfall 31 per cent higher than average for the 1961 to 1990 period. According to the Bureau of Meteorology’s Annual Climate Statement, released in February 2026, 2025 was the fourth-warmest year on record in Australia. Brisbane pool owners have experienced both climatic conditions, and some of them may observe the consequences in their pools. Heavy rains, hot days and humid nights provide a nearly perfect environment for cloudy water and algae. Knowing why this phenomenon takes place will help you keep your pool water clear despite the weather conditions.
The Effects of Rain and Heat on the Pool Water
Apart from simply filling the pool, a rainstorm has several effects on it that pool servicing Brisbane technicians know well. First of all, rain dilutes chlorine concentration and changes pH value. In addition, rain washes leaves, garden fertilisers and other contaminants into your swimming pool. Phosphate compounds in such runoffs stimulate the growth of algae, so you may observe green water after only a few days.
Furthermore, warm water stimulates the growth of algae. Moreover, sunny weather decreases chlorine concentration, because chlorine decomposes under the effect of UV rays. As humid night makes the water temperature not fall, a relatively minor problem of Friday turns into a severe issue by Monday.
If your pool behaved well in July but gives you trouble in January, this is one of the main reasons why it happens. Those Brisbane pool owners who understand the connection between the climate and the chemistry of water manage to identify issues at an early stage and fix them quickly.
Storm Season Versus the Quiet Period
The storm season in Brisbane is usually from November to March. Storms, as well as strong winds, carry leaves and other rubbish in the water, and the rainstorms wash out the dirt from paving and lawns. Besides, saltwater pools lose some amount of salt with overflow and splash-out of water, and so chlorine production decreases precisely at this time.
As for the quiet period, the demand for chlorine reduces significantly, and algae grows more slowly. In addition, pumps work for a shorter time during these months. Therefore, the period of November to March is the best moment to clean filters and replace necessary pool equipment.
Usually, fortnightly pool maintenance cannot fit the seasonal changes.
The Chemistry Behind a Pool That Turns Green Overnight
The free chlorine that’s the heart of your sanitiser is what actively kills off bacteria and algae. Stabiliser protects that chlorine from getting cooked by the sunlight, but too much of it and the chlorine will start to slow right down. You need to keep your pH and alkalinity spot on to let the chlorine do its job and keep your pool surfaces and fittings safe.
When one of these numbers starts drifting off the scale, the others will usually be following close behind. If the pH spike after a big rainstorm means the chlorine is running slowly, then algae is just waiting for an opening to take over. By keeping on top of your testing between visits, you can catch any tiny changes before they turn into a costly rescue mission to fix a green pool.
To keep most problems at bay in the wetter months, here are a few simple habits to get into:
Equipment Working Its Heart Out in a Subtropical Climate
Your pump, filter and salt chlorinator are all working longer hours than usual in a hot Brisbane summer. And that extra mileage on them is going to wear out those seals, bearings and motors faster than you might expect. Filters also get clogged up faster when there are storms sending all that fine dirt into the water.
Storms also bring a whole new level of electrical risk that doesn’t get as much attention as it should. Lightning and power surges can damage those control boards and chlorinator cells without any warning at all. And if the water gets into those equipment covers because they’re not sealed properly, you might not even notice until weeks later when you start to get faults.
If your equipment is working this hard, then it’s probably a good time to take a closer look at your running costs. Variable speed pumps can make a huge difference in the long run by using a lot less energy than those old single-speed models. And running your pumps during off-peak hours if you can will make a big dent in your summer power bills.
Brisbane’s climate is unlikely to get any easier on pool owners in the near future, so it’s well worth planning your pool care around the weather rather than by the calendar if you want to keep your pool water clearer and avoid those costly surprises.
