How To Prevent Algae Growth In A Pool Without Chemicals

Why Algae Grows in Pools and Why You Should Prevent It

As a pool owner in New Zealand, dealing with algae growth is a common issue, especially during the warmer months. Algae spores are always present in the environment, and given the right conditions—warm temperatures, sunlight, and stagnant water—they can quickly turn your sparkling pool into a green, murky mess.

Preventing algae growth without using chemicals is not only possible but also a great way to make your pool safer for swimmers and reduce reliance on chlorine and algaecides. Here’s how you can maintain a clean, algae-free pool naturally.

Improve Circulation and Filtration

Poor water circulation is one of the main reasons algae take hold in a pool. Making sure your pool water is always moving helps prevent algae from settling and growing.

Run your filter regularly – Running your pool pump and filter for at least 8–12 hours a day ensures water is constantly moving, which deprives algae of the stagnant conditions it needs to thrive. If you have a variable speed pump, running it on a lower speed for longer can be more energy efficient.
Target dead spots – Algae often develops in areas with poor circulation, such as steps, corners, and around ladders. Use a brush to manually stir up these areas and improve overall water movement.
Keep your filter clean – A clogged or dirty filter won’t work efficiently. Depending on your filter type, backwashing (for sand filters) or regular cartridge cleaning ensures algae spores and debris are removed from the water.

For local supplies and maintenance advice, check out Splash Pool & Spa or Pool & Spa Warehouse NZ.

Regular Brushing and Vacuuming

Physically removing algae before it becomes a problem is one of the best ways to keep your pool clean naturally.

Brush the pool walls and floor – Using a pool brush, scrub all surfaces at least once a week to dislodge any algae spores before they have a chance to spread.
Vacuum the pool – Whether you use a manual vacuum or an automatic cleaner, removing debris keeps algae from feeding on organic material in the water.

Local retailers such as Para Rubber offer a range of pool maintenance tools, including brushes and vacuums.

Use a Solar Cover

Sunlight encourages algae growth by providing the warmth it thrives on. A solar pool cover or shade can help reduce algae growth by limiting direct sunlight exposure.

Solar covers – Not only do they help keep out debris and reduce evaporation, but they also prevent excessive UV light penetration, which algae need to grow.
Shade sails – If installing a permanent cover isn’t an option, consider using shade sails over part of the pool to cut down on light exposure.

You can find pool covers and shade solutions at The Warehouse or Mitre 10.

Maintain Proper Water Balance

Even without chemicals like chlorine, keeping your pool’s water properly balanced is essential for algae prevention.

Check pH levels – A pH level between 7.2 and 7.6 helps keep your pool water in an optimal state. High pH can encourage algae growth, so regular testing is important.
Monitor phosphate levels – Phosphates are a key food source for algae. While some pool owners use phosphate removers, you can naturally minimise phosphates by keeping leaves, dirt, and organic matter out of the pool.
Use natural alternatives – Adding baking soda (to maintain pH) or vinegar (to control algae in small amounts) can help balance water chemistry naturally.

For pool water testing kits and natural treatment options, check out Swimming Pool Warehouse.

Introduce Natural Algae Inhibitors

There are a few effective natural methods to keep algae at bay:

Barley straw – Placing a small bundle of barley straw in your pool can help prevent algae growth as it releases natural compounds that inhibit algae development.
Essential oils – Some natural pool owners find that adding small amounts of tea tree or eucalyptus oil discourages algae formation.
Hydrogen peroxide – While not completely chemical-free, food-grade hydrogen peroxide is an alternative to chlorine that helps keep water clean.

These alternatives should be used carefully but can be found in stores like HealthPost NZ for natural cleaning solutions.

Rinse Off Before Swimming

Organic material from swimmers—such as body oils, sunscreen, and sweat—can contribute to algae growth. Encourage family and guests to rinse off before entering the pool. If your home allows, installing an outdoor shower near the pool makes this easier.

Check Bunnings NZ for outdoor shower options that fit your space.

Keep Debris Out of the Pool

Fallen leaves, dirt, and other organic debris introduce nutrients that feed algae. Preventing this is key to a cleaner pool.

Use a pool skimmer – Skimming the surface daily helps remove organic matter before it sinks and decomposes.
Trim overhanging trees and plants – Reducing the amount of foliage around your pool minimises the risk of leaves falling into the water.
Install a pool cover – A simple solution that keeps out debris when the pool isn’t in use.

For skimmers and covers, visit Trade Tested or Bermuda Lifestyle.

Enjoy a Clean, Chemical-Free Pool

With these natural methods, you can keep your pool algae-free without relying on harsh chemicals. Regular maintenance, proper circulation, and a proactive approach will ensure your pool stays clean, clear, and ready for swimming all year round.

If you’re looking for more pool care resources in New Zealand, be sure to explore local retailers and suppliers to find the best eco-friendly products for your pool.

Pool Owners New Zealand