Why Does My Pool Keep Going Green?

There’s nothing more frustrating than walking outside, ready for a relaxing swim, only to find your pool looking green and murky. A green pool is a common problem for many Australian pool owners, especially during the warmer months when pools get plenty of use and algae can grow quickly.

The good news? In most cases, a green pool is caused by a few common issues that are usually easy to identify and fix.

1. Your Pool Pump Isn’t Running Long Enough

One of the most common reasons a pool turns green is simply not running the pump long enough each day.

Your pump and filtration system are responsible for circulating the water, removing debris, and helping distribute chemicals evenly throughout the pool. If the water isn’t circulating properly, algae can quickly start to grow.

As a general guide for Australian pools, your pump should run around 8–10 hours per day in summer and 4–6 hours in cooler months. If your pool keeps going green, increasing your pump’s run time may help keep the water clearer and healthier.

2. Chlorine Output From Your Salt Chlorinator Is Too Low

If you have a saltwater pool, your salt chlorinator is responsible for producing chlorine to sanitise the water.

Sometimes the system may be running, but the chlorine output setting is too low to keep up with demand—especially during hot weather, heavy pool use, or after rain.

Signs your chlorinator may be set too low include:

• Cloudy or slightly green water

• Algae forming on pool walls

• Low chlorine readings during water testing

Increasing the output level on your chlorinator can often solve the issue and help maintain proper sanitation.

3. Your Salt Cell May Be Worn Out

Salt cells don’t last forever. Over time, the plates inside the cell gradually wear down and become less effective at producing chlorine. You will clearly see if any of the cell plates are corroded down shorter than the others - usually the first to go is the centre plate.

Most salt cells typically last 3–5 years, depending on usage, maintenance, and water balance.

If your pool is constantly struggling to maintain chlorine levels—even when the chlorinator is set high—it may be a sign that your salt cell is reaching the end of its life and needs replacing.

Regularly checking and cleaning the salt cell can help extend its lifespan, but eventually replacement is unavoidable.

4. Water Balance Could Be Off

Another factor that can contribute to green pool water is imbalanced pool chemistry. If your pH, alkalinity, phosphate or stabiliser levels are out of range, chlorine may not work effectively.

This means even if your chlorinator is producing chlorine, it may not be doing its job properly.

Regular water testing helps ensure everything stays balanced and your sanitizer can work at its best.

Keeping Your Pool Clear and Healthy

Preventing a green pool is much easier than fixing one. A few simple habits can make a big difference:

• Run your pump long enough each day

• Check your chlorinator output regularly

• Inspect and clean your salt cell

• Test your water frequently

• Keep your pool free of leaves and debris

If your pool keeps turning green despite your best efforts, it might be time for a professional water test or equipment check to identify the underlying issue.

With the right maintenance and equipment settings, you can keep your pool crystal clear and ready to enjoy all year round.